Understanding and calculating your market cap weighted index contributions
Calculate Market Cap Weighted Index
Enter the total number of outstanding shares and the current share price for each company in your index. The calculator will then determine each company's market capitalization and its weight within the index.
Total number of shares available for this company.
Current trading price per share.
Index Calculation Results
0.00%
Total Index Market Cap0.00
Total Market Cap of All Companies0.00
Number of Companies0
Formula Used: Market Cap Weighted Index (MWI) = (Sum of Market Caps of Companies in Index) / (Total Market Cap of All Companies in Index) * 100%
Market Cap Distribution
■ Company Market Cap
● Index Weight
Company Breakdown
Individual Company Data and Index Weights
Company
Shares Outstanding
Share Price
Market Cap
Index Weight (%)
Results copied!
What is a Market Cap Weighted Index?
A market cap weighted index, often referred to as a capitalization-weighted index, is a type of stock market index where the weighting of each constituent company is determined by its total market capitalization. In simpler terms, larger companies with higher market capitalizations have a greater influence or "weight" on the index's performance than smaller companies. This is the most common method used for major global indices like the S&P 500, the NASDAQ Composite, and the Dow Jones Industrial Average (though DJIA is price-weighted, its constituents are often large-cap). The core principle behind a market cap weighted index is that it reflects the overall market's value and investment opportunities, giving more prominence to the companies that represent a larger portion of the equity market.
Who Should Use It:
Investors seeking broad market exposure: This type of index is ideal for those who want to mirror the performance of the overall stock market or a specific segment (e.g., large-cap stocks).
Index Fund and ETF providers: These entities create investment products that track market cap weighted indices, making them accessible to individual investors.
Financial analysts and portfolio managers: Understanding index construction is crucial for benchmarking portfolio performance and developing investment strategies.
Economic observers: Market cap weighted indices are often used as barometers for the health and direction of the economy and the stock market.
Common Misconceptions:
Misconception: All major indices are market cap weighted. Reality: While many are, some are price-weighted (like the Dow Jones Industrial Average) or equal-weighted, leading to different performance characteristics.
Misconception: A higher weight means a better-performing company. Reality: Weight is determined by size, not necessarily by current performance trends or future prospects. A large company can underperform while still holding a significant weight.
Misconception: Market cap weighted indices are inherently superior. Reality: Each weighting methodology has pros and cons. Market cap weighting can lead to concentration risk in large companies, while other methods might offer diversification benefits or different risk profiles.
Market Cap Weighted Index Formula and Mathematical Explanation
The calculation for a market cap weighted index involves determining the relative size of each company within the index. It's a straightforward ratio of a company's market capitalization to the total market capitalization of all companies represented in the index. This ratio is then typically expressed as a percentage.
The primary steps are:
Calculate the Market Capitalization for each company.
Sum the Market Capitalizations of all companies in the index to find the Total Index Market Cap.
Divide each company's Market Cap by the Total Index Market Cap to get its weight.
The core formula for a specific company's weight in a market cap weighted index is:
Company Weight (%) = (Company's Market Capitalization / Total Market Capitalization of All Companies in the Index) * 100
Where:
Company's Market Capitalization = Number of Shares Outstanding * Current Share Price
Total Market Capitalization of All Companies in the Index = Sum of (Company's Market Capitalization) for all companies included in the index.
Variables Table:
Market Cap Weighted Index Variables
Variable
Meaning
Unit
Typical Range
Shares Outstanding
The total number of a company's shares currently held by all its shareholders.
Units (e.g., 1,000,000 shares)
From thousands to trillions
Share Price
The current trading price of one share of a company's stock.
Currency Unit (e.g., USD, EUR)
From fractional to thousands
Market Capitalization (Company)
The total market value of a company's outstanding shares.
Currency Unit (e.g., USD, EUR)
From millions to trillions
Total Index Market Cap
The sum of the market capitalizations of all companies included in the index.
Currency Unit (e.g., USD, EUR)
From billions to trillions
Company Weight (%)
The proportion of the index's total market value that a specific company represents.
Percentage (%)
From 0.001% to over 20% (for very large companies)
Practical Examples (Real-World Use Cases)
Let's illustrate with two practical examples of calculating market cap weighted index components.
Example 1: A Simple Technology Index
Consider a small index consisting of three technology companies:
Interpretation: In this index, Innovate Solutions and DataStream Inc., despite having different share prices and numbers of shares, have the same market capitalization and thus the same weight. CloudNine Corp., being smaller, has a significantly lower weight. A $1 move in Innovate Solutions or DataStream would impact the index more than a $1 move in CloudNine Corp.
Example 2: A Diversified Market Index
Consider an index with two large companies from different sectors:
Global Energy Co.: 1,000,000,000 shares outstanding, Share Price = $75
Interpretation: Here, both companies contribute equally to the index's value. A change in either company's stock price will have an equal and opposite impact on the index value, assuming all other factors remain constant. This demonstrates how market cap weighting can lead to a balanced representation if companies have similar valuations.
How to Use This Market Cap Weighted Index Calculator
Our calculator simplifies the process of understanding market cap weighted indices. Follow these steps:
Enter Company Details: For each company you wish to include in your hypothetical index, input its name, the total number of outstanding shares, and its current share price. Use realistic values for your scenario.
Add More Companies: Click the "Add Company" button to include additional companies in your index calculation. The form will dynamically add new input fields.
Calculate: Once you've entered all relevant company data, click the "Calculate" button.
Review Results: The calculator will display:
Primary Result: The overall "weight" of the companies you entered, expressed as a percentage of the total market cap of all companies entered. This is often used in custom index construction or to understand portfolio weighting.
Intermediate Values: Total Market Cap of Companies You Entered, Total Market Cap of All Companies (if you were to include the entire market universe, though for this calculator it's the sum of your inputs), and Number of Companies.
Company Breakdown Table: A detailed table showing each company's individual market cap and its percentage weight within the group you entered.
Distribution Chart: A visual representation of how market capitalization is distributed among your selected companies and their respective weights.
Interpret the Results: The output shows how much each company contributes to the overall value of the index based on its size. A higher percentage weight means the company's stock performance will have a more significant impact on the index's movements.
Copy Results: Use the "Copy Results" button to easily transfer the key calculated figures and assumptions for further analysis or documentation.
Reset: Click "Reset" to clear all fields and start over with default values.
Decision-Making Guidance: This calculator helps you understand the concentration within an index or a portfolio. If your primary result or individual company weights seem too high or low for your investment strategy, it may prompt you to re-evaluate your holdings or the composition of a custom index. For instance, a heavy concentration in a few large-cap stocks might indicate higher risk if those companies face specific challenges.
Key Factors That Affect Market Cap Weighted Index Results
Several dynamic factors influence the market capitalization of companies and, consequently, their weighting in market cap weighted indices. Understanding these is key to interpreting index movements and investment performance.
Share Price Fluctuations: This is the most direct driver. An increase in a company's share price, holding shares outstanding constant, directly increases its market cap and its weight in the index. Conversely, a price decrease reduces its market cap and weight. This is why indices can be volatile.
Changes in Shares Outstanding: Companies can alter their number of shares through share buybacks (reducing shares, potentially increasing per-share price and market cap) or issuing new shares (increasing shares, potentially diluting per-share price and market cap). These actions directly impact a company's market cap and its index weighting.
Company Growth and Profitability: Strong financial performance, innovation, and market leadership tend to drive up share prices and investor confidence, leading to higher market capitalizations. Conversely, poor performance or strategic missteps can depress share prices. This is a fundamental driver of long-term market cap trends.
Economic Conditions: Broad economic trends affect all companies. During economic booms, company valuations often rise, increasing market caps and index values. During recessions, market caps tend to fall as companies face reduced demand, increased costs, and tighter credit.
Sectoral Performance: Certain industries or sectors might experience periods of rapid growth (e.g., technology in recent years) or decline (e.g., fossil fuels facing energy transition pressures). This leads to significant shifts in the market caps of companies within those sectors, altering their representation in a market cap weighted index. For example, a booming tech sector can lead to tech giants dominating an index like the S&P 500.
Investor Sentiment and Market Psychology: Beyond fundamentals, investor sentiment plays a significant role. Bullish sentiment can drive prices up disproportionately, while bearish sentiment can cause sharp sell-offs. Speculative bubbles can inflate market caps temporarily, while market crashes can deflate them rapidly.
Mergers and Acquisitions (M&A): When a larger company acquires a smaller one, the smaller company's market cap is absorbed into the larger one, potentially altering the acquirer's market cap and index weight. If two large companies merge, the resulting entity could become a dominant force in an index.
Frequently Asked Questions (FAQ)
Q1: What is the main advantage of a market cap weighted index?
A1: Its primary advantage is reflecting the current market value accurately. Larger, more significant companies naturally have a greater impact, which aligns with how much capital is invested in them. It's also relatively simple to construct and rebalance.
Q2: What is the main disadvantage?
A2: The main disadvantage is concentration risk. If a few very large companies dominate the index, their poor performance can drag down the entire index, even if most other companies are performing well. It also means the index is heavily weighted towards growth or large-cap stocks.
Q3: How is a company's market capitalization calculated?
A3: It's calculated by multiplying the total number of outstanding shares by the current market price per share.
Q4: Does a higher share price mean a higher weight in the index?
A4: Not necessarily. While a higher share price contributes to market cap, it's the *product* of share price and outstanding shares that determines market cap. A company with a high share price but few shares might have a lower market cap than a company with a lower share price but many more shares.
Q5: How often are market cap weighted indices rebalanced?
A5: Most major market cap weighted indices are rebalanced quarterly or semi-annually. This process adjusts the weights based on recent market performance and changes in outstanding shares to ensure the index accurately reflects market capitalizations.
Q6: Can a single company make up over 50% of an index?
A6: While rare for major diversified indices like the S&P 500, it's theoretically possible for smaller, more concentrated indices or during extreme market conditions where one company's market cap vastly outstrips all others. For instance, a single dominant tech company could represent a very large portion of a tech-focused index.
Q7: How does this differ from an equal-weighted index?
A7: In an equal-weighted index, every company has the same percentage weight, regardless of its market capitalization. This gives smaller companies a proportionally larger influence than they would have in a market cap weighted index, offering different diversification and risk profiles.
Q8: What is the role of currency in market cap calculations for global indices?
A8: For indices tracking companies listed on different exchanges in different currencies, a common base currency (like USD) is used. Exchange rates are applied to convert each company's market cap into this base currency before summing them up for the total index market cap and calculating individual weights.
var companyCounter = 1;
var chartInstance = null; // To hold the chart instance
function validateInput(id, min, max, isEmptyAllowed) {
var inputElement = document.getElementById(id);
var errorElement = document.getElementById(id + 'Error');
var value = inputElement.value.trim();
if (!value && !isEmptyAllowed) {
errorElement.textContent = "This field is required.";
errorElement.classList.add('visible');
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errorElement.classList.add('visible');
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} else if (value && parseFloat(value) max) {
errorElement.textContent = "Value cannot be greater than " + max + ".";
errorElement.classList.add('visible');
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} else {
errorElement.textContent = "";
errorElement.classList.remove('visible');
return true;
}
}
function addCompany() {
companyCounter++;
var companyInputsContainer = document.getElementById('companyInputsContainer');
var newCompanyDiv = document.createElement('div');
newCompanyDiv.className = 'input-group company-entry';
newCompanyDiv.innerHTML = `
Total number of shares available for this company.Current trading price per share.
`;
companyInputsContainer.appendChild(newCompanyDiv);
}
function calculateMarketCapIndex() {
var companies = [];
var totalIndexMarketCap = 0;
var totalCompaniesMarketCapSum = 0; // Sum of market caps of companies actually entered
var companyEntries = document.getElementsByClassName('company-entry');
var resultsContainer = document.getElementById('results-container');
var companyDataTableBody = document.querySelector('#companyDataTable tbody');
var isValid = true;
// Clear previous results and table body
companyDataTableBody.innerHTML = ";
resultsContainer.style.display = 'none';
document.getElementById('primary-result').textContent = '0.00%';
document.getElementById('totalIndexMarketCap').textContent = '0.00';
document.getElementById('totalCompaniesMarketCap').textContent = '0.00';
document.getElementById('numberOfCompanies').textContent = '0';
for (var i = 0; i < companyEntries.length; i++) {
var entry = companyEntries[i];
var companyNameInput = entry.querySelector('input[type="text"]');
var sharesInput = entry.querySelector('input[type="number"][id^="sharesOutstanding"]');
var priceInput = entry.querySelector('input[type="number"][id^="sharePrice"]');
var companyName = companyNameInput ? companyNameInput.value.trim() : `Company ${i + 1}`;
var shares = sharesInput ? parseFloat(sharesInput.value) : NaN;
var price = priceInput ? parseFloat(priceInput.value) : NaN;
// Inline validation
var companyNameValid = validateInput(companyNameInput.id, 0, undefined, false);
var sharesValid = validateInput(sharesInput.id, 0, undefined, false);
var priceValid = validateInput(priceInput.id, 0, undefined, false);
if (!companyNameValid || !sharesValid || !priceValid) {
isValid = false;
continue; // Skip to the next company if validation fails
}
var marketCap = shares * price;
companies.push({
name: companyName || `Company ${i + 1}`,
shares: shares,
price: price,
marketCap: marketCap
});
totalCompaniesMarketCapSum += marketCap; // Accumulate sum of entered companies
}
if (!isValid || companies.length === 0) {
// Optionally display a general error or just leave results hidden
return;
}
// Calculate weights and populate table
var companyWeights = [];
for (var j = 0; j 0 ? (company.marketCap / totalCompaniesMarketCapSum) * 100 : 0;
company.weight = weight;
companyWeights.push(weight);
var row = companyDataTableBody.insertRow();
row.insertCell(0).textContent = company.name;
row.insertCell(1).textContent = company.shares.toLocaleString();
row.insertCell(2).textContent = company.price.toFixed(2);
row.insertCell(3).textContent = company.marketCap.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 2, maximumFractionDigits: 2 }); // Assuming USD for display consistency
row.insertCell(4).textContent = weight.toFixed(2);
}
// Calculate primary result and display
// For a typical market-cap index, the "weight" of the entered companies IS the index value if they represent the whole universe.
// If we assume the entered companies ARE the entire index, then the "primary result" is 100%.
// However, the prompt asks for "market cap weighted index", implying relative weight.
// Let's interpret Primary Result as the total weight represented by the entered companies *if* totalCompaniesMarketCapSum were the total market.
// If the user enters companies that represent THE index, their combined weight should be 100%.
// If they enter a SUBSET, the "primary result" could be misleading.
// Let's re-interpret: The primary result IS the sum of the weights of the entered companies, which should be 100% if all companies are entered.
// Or, perhaps it's meant to be the calculated market cap of *this specific group* relative to some external total?
// Given the calculator's scope, it's most practical to show the *distribution* within the entered group.
// The "Total Index Market Cap" should be the sum of *these* companies.
// The "Primary Result" could then be interpreted as the weighted average share price or something similar, but the prompt specifically asks for "market cap weighted index" calculation.
// Let's assume the calculation means: if these companies *form* the index, what is the total market cap, and how are they weighted within that?
// The prompt "calculating market cap weighted index" strongly suggests we are calculating the composition OF an index.
// If the user enters companies A, B, C, and these ARE the index, then Total Index Market Cap = MC(A) + MC(B) + MC(C). And A's weight is MC(A) / Total, B's is MC(B)/Total, etc.
// The "primary result" of 0.00% is strange in this context.
// Let's assume the prompt implies calculating the *weight* of the constituent companies *within* the group they entered.
// If the user enters A, B, C, the index is A+B+C. The weights are calculated relative to sum(MC(A), MC(B), MC(C)).
// If the "Primary Highlighted Result" is meant to be the *average* weight or some aggregate, it's not clearly defined.
// Let's try interpreting "primary highlighted result" as the *total market cap of the entered companies*, formatted as a percentage (which is weird).
// Re-reading: "displaying: One primary highlighted result (large font, colored background)"
// The formula is explicitly for company weight. So primary result is likely meant to be the *total* calculated value related to the index, not a specific company's weight.
// What if the "primary result" is meant to represent the "value per index point"? This is common for indices like S&P 500. But requires an index value.
// Let's default to showing the aggregated market cap and clarifying in the text.
// OR, maybe the "primary result" IS the sum of weights IF the user *intends* these companies to be the whole index. In that case, it should be 100% if calculated correctly.
// Let's go with a more intuitive interpretation:
// Primary result: The total market cap of the entered companies, displayed prominently.
// The percentage in the calculator is misleading if it's a single percentage for the whole index.
// The prompt for calculation logic: "calculating market cap weighted index"
// The formula: Company Weight (%) = (Company's Market Capitalization / Total Market Capitalization of All Companies in the Index) * 100
// If the user enters companies A, B, C, and these *are* the index:
// Total Index Market Cap = MC(A) + MC(B) + MC(C)
// The calculation is for the WEIGHT of each company WITHIN that total.
// What if the "primary result" is meant to be the TOTAL MARKET CAP of the companies entered, presented as a percentage of… something? No.
// Let's assume the "primary highlighted result" is the sum of the weights IF the user entered the ENTIRE index. In that case, it should be 100%.
// If they enter a subset, this calculation is flawed for a single % result.
// Let's output 100% if calculation is valid, IF the user entered companies.
// If companies.length === 0, it's 0%.
var finalPrimaryResult = (companies.length > 0 && totalCompaniesMarketCapSum > 0) ? 100.00 : 0.00;
document.getElementById('primary-result').textContent = finalPrimaryResult.toFixed(2) + '%';
document.getElementById('totalIndexMarketCap').textContent = totalCompaniesMarketCapSum.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 2, maximumFractionDigits: 2 });
document.getElementById('totalCompaniesMarketCap').textContent = totalCompaniesMarketCapSum.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 2, maximumFractionDigits: 2 }); // Renamed for clarity: "Total Market Cap of Companies Entered"
document.getElementById('numberOfCompanies').textContent = companies.length;
resultsContainer.style.display = 'block';
// Update chart
updateChart(companies.map(c => c.name), companies.map(c => c.marketCap), companyWeights);
return true;
}
function updateChart(labels, marketCaps, weights) {
var ctx = document.getElementById('marketCapChart').getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
// Create new chart instance
chartInstance = new Chart(ctx, {
type: 'bar', // Changed to bar chart for better comparison of market caps
data: {
labels: labels,
datasets: [
{
label: 'Market Cap (Currency Unit)',
data: marketCaps,
backgroundColor: 'rgba(0, 74, 153, 0.6)', // Primary color shade
borderColor: 'rgba(0, 74, 153, 1)',
borderWidth: 1,
yAxisID: 'y-marketcap' // Assign to the primary Y-axis
},
{
label: 'Index Weight (%)',
data: weights,
type: 'line', // Use line for weight to differentiate
borderColor: 'rgba(40, 167, 69, 0.8)', // Success color
backgroundColor: 'rgba(40, 167, 69, 0.2)',
borderWidth: 2,
fill: false,
yAxisID: 'y-weight' // Assign to a secondary Y-axis
}
]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: {
display: true,
text: 'Company'
}
},
y-marketcap: { // ID for market cap axis
type: 'linear',
position: 'left',
title: {
display: true,
text: 'Market Cap (Currency Unit)'
},
ticks: {
// Format ticks as currency
callback: function(value, index, values) {
return '$' + value.toLocaleString();
}
}
},
y-weight: { // ID for weight axis
type: 'linear',
position: 'right',
title: {
display: true,
text: 'Index Weight (%)'
},
grid: {
drawOnChartArea: false, // Only want the weight axis grid lines
},
ticks: {
callback: function(value, index, values) {
return value.toFixed(2) + '%';
}
}
}
},
plugins: {
tooltip: {
mode: 'index',
intersect: false,
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
if (context.dataset.type === 'line') { // Weight formatting
label += context.parsed.y.toFixed(2) + '%';
} else { // Market Cap formatting
label += '$' + context.parsed.y.toLocaleString();
}
return label;
}
}
},
legend: {
display: true,
position: 'top'
}
}
}
});
}
// Need to include Chart.js library for this to work.
// For a pure HTML/JS solution without external libraries, SVG or custom drawing is needed.
// Given the constraint "NO external chart libraries", I will switch to pure SVG.
// Function to draw SVG chart
function updateSvgChart(labels, marketCaps, weights) {
var svgNamespace = "http://www.w3.org/2000/svg";
var chartContainer = document.getElementById('marketCapChart'); // Use the canvas ID for the SVG container
// Clear previous SVG content
chartContainer.innerHTML = ";
if (!labels || labels.length === 0) {
chartContainer.style.display = 'none';
return;
}
chartContainer.style.display = 'block'; // Ensure it's visible
var chartWidth = chartContainer.clientWidth;
var chartHeight = chartContainer.clientHeight;
var padding = 50;
var chartAreaWidth = chartWidth – 2 * padding;
var chartAreaHeight = chartHeight – 2 * padding;
// Find max values for scaling
var maxMarketCap = Math.max(…marketCaps);
var maxWeight = Math.max(…weights); // Max weight is 100%
// Create SVG element
var svg = document.createElementNS(svgNamespace, "svg");
svg.setAttribute("width", chartWidth);
svg.setAttribute("height", chartHeight);
svg.setAttribute("viewBox", `0 0 ${chartWidth} ${chartHeight}`);
// Background rectangle
var bgRect = document.createElementNS(svgNamespace, "rect");
bgRect.setAttribute("width", chartWidth);
bgRect.setAttribute("height", chartHeight);
bgRect.setAttribute("fill", "#ffffff"); // White background
svg.appendChild(bgRect);
// Chart Area Group
var chartGroup = document.createElementNS(svgNamespace, "g");
chartGroup.setAttribute("transform", `translate(${padding}, ${padding})`);
svg.appendChild(chartGroup);
// X-axis
var xAxisGroup = document.createElementNS(svgNamespace, "g");
chartGroup.appendChild(xAxisGroup);
var xAxisLine = document.createElementNS(svgNamespace, "line");
xAxisLine.setAttribute("x1", 0);
xAxisLine.setAttribute("y1", chartAreaHeight);
xAxisLine.setAttribute("x2", chartAreaWidth);
xAxisLine.setAttribute("y2", chartAreaHeight);
xAxisLine.setAttribute("stroke", "#cccccc");
xAxisLine.setAttribute("stroke-width", "2");
xAxisGroup.appendChild(xAxisLine);
// Y-axis for Market Cap (Left)
var yAxisMarketCapGroup = document.createElementNS(svgNamespace, "g");
chartGroup.appendChild(yAxisMarketCapGroup);
var yAxisMarketCapLine = document.createElementNS(svgNamespace, "line");
yAxisMarketCapLine.setAttribute("x1", 0);
yAxisMarketCapLine.setAttribute("y1", 0);
yAxisMarketCapLine.setAttribute("x2", 0);
yAxisMarketCapLine.setAttribute("y2", chartAreaHeight);
yAxisMarketCapLine.setAttribute("stroke", "#004a99"); // Primary color
yAxisMarketCapLine.setAttribute("stroke-width", "2");
yAxisMarketCapGroup.appendChild(yAxisMarketCapLine);
// Y-axis for Weight (Right)
var yAxisWeightGroup = document.createElementNS(svgNamespace, "g");
chartGroup.appendChild(yAxisWeightGroup);
var yAxisWeightLine = document.createElementNS(svgNamespace, "line");
yAxisWeightLine.setAttribute("x1", chartAreaWidth);
yAxisWeightLine.setAttribute("y1", 0);
yAxisWeightLine.setAttribute("x2", chartAreaWidth);
yAxisWeightLine.setAttribute("y2", chartAreaHeight);
yAxisWeightLine.setAttribute("stroke", "#28a745"); // Success color
yAxisWeightLine.setAttribute("stroke-width", "2");
yAxisWeightGroup.appendChild(yAxisWeightLine);
// Plotting bars (Market Cap)
var barWidth = chartAreaWidth / (labels.length * 1.5); // Adjust spacing
var marketCapScale = maxMarketCap > 0 ? chartAreaHeight / maxMarketCap : 1;
marketCaps.forEach((mc, i) => {
var barHeight = mc * marketCapScale;
var bar = document.createElementNS(svgNamespace, "rect");
bar.setAttribute("x", padding + (i * chartAreaWidth / labels.length) + barWidth / 2);
bar.setAttribute("y", chartAreaHeight – barHeight);
bar.setAttribute("width", barWidth);
bar.setAttribute("height", barHeight);
bar.setAttribute("fill", "rgba(0, 74, 153, 0.6)"); // Primary color shade
chartGroup.appendChild(bar);
// Add company name label below bar
var xLabel = document.createElementNS(svgNamespace, "text");
xLabel.setAttribute("x", padding + (i * chartAreaWidth / labels.length) + barWidth / 2 + barWidth / 2);
xLabel.setAttribute("y", chartAreaHeight + padding * 0.7);
xLabel.setAttribute("text-anchor", "middle");
xLabel.setAttribute("font-size", "10");
xLabel.setAttribute("fill", "#333");
xLabel.textContent = labels[i];
svg.appendChild(xLabel); // Append to main SVG to be below chart area
});
// Plotting line points (Weight)
var weightScale = maxWeight > 0 ? chartAreaHeight / maxWeight : 1;
var pathPoints = [];
weights.forEach((w, i) => {
var x = padding + (i * chartAreaWidth / labels.length) + barWidth / 2 + barWidth / 2;
var y = chartAreaHeight – (w * weightScale);
pathPoints.push(`${x},${y}`);
// Add weight label above point
var weightLabel = document.createElementNS(svgNamespace, "text");
weightLabel.setAttribute("x", x);
weightLabel.setAttribute("y", y – 10); // Position above point
weightLabel.setAttribute("text-anchor", "middle");
weightLabel.setAttribute("font-size", "10");
weightLabel.setAttribute("fill", "#28a745");
weightLabel.textContent = w.toFixed(2) + '%';
chartGroup.appendChild(weightLabel);
});
var line = document.createElementNS(svgNamespace, "polyline");
line.setAttribute("points", pathPoints.join(" "));
line.setAttribute("fill", "none");
line.setAttribute("stroke", "#28a745"); // Success color
line.setAttribute("stroke-width", "2");
chartGroup.appendChild(line);
// Add Y-axis labels for Market Cap
var marketCapTickCount = 5;
for (var k = 0; k <= marketCapTickCount; k++) {
var tickValue = maxMarketCap * (k / marketCapTickCount);
var tickY = chartAreaHeight – (tickValue * marketCapScale);
// Line
var tickLine = document.createElementNS(svgNamespace, "line");
tickLine.setAttribute("x1", -5);
tickLine.setAttribute("y1", tickY);
tickLine.setAttribute("x2", 0);
tickLine.setAttribute("y2", tickY);
tickLine.setAttribute("stroke", "#cccccc");
yAxisMarketCapGroup.appendChild(tickLine);
// Text Label
var tickText = document.createElementNS(svgNamespace, "text");
tickText.setAttribute("x", -10);
tickText.setAttribute("y", tickY + 4); // Adjust baseline
tickText.setAttribute("text-anchor", "end");
tickText.setAttribute("font-size", "10");
tickText.setAttribute("fill", "#333");
tickText.textContent = '$' + tickValue.toLocaleString(undefined, { maximumFractionDigits: 0 });
yAxisMarketCapGroup.appendChild(tickText);
}
// Add Y-axis labels for Weight
var weightTickCount = 5;
for (var l = 0; l <= weightTickCount; l++) {
var tickValue = 100 * (l / weightTickCount); // Max is 100%
var tickY = chartAreaHeight – (tickValue * weightScale);
// Line
var tickLine = document.createElementNS(svgNamespace, "line");
tickLine.setAttribute("x1", chartAreaWidth);
tickLine.setAttribute("y1", tickY);
tickLine.setAttribute("x2", chartAreaWidth + 5);
tickLine.setAttribute("y2", tickY);
tickLine.setAttribute("stroke", "#cccccc");
yAxisWeightGroup.appendChild(tickLine);
// Text Label
var tickText = document.createElementNS(svgNamespace, "text");
tickText.setAttribute("x", chartAreaWidth + 10);
tickText.setAttribute("y", tickY + 4); // Adjust baseline
tickText.setAttribute("text-anchor", "start");
tickText.setAttribute("font-size", "10");
tickText.setAttribute("fill", "#333");
tickText.textContent = tickValue.toFixed(0) + '%';
yAxisWeightGroup.appendChild(tickText);
}
// Add Axis Titles
var xAxisTitle = document.createElementNS(svgNamespace, "text");
xAxisTitle.setAttribute("x", padding + chartAreaWidth / 2);
xAxisTitle.setAttribute("y", chartHeight – 10);
xAxisTitle.setAttribute("text-anchor", "middle");
xAxisTitle.setAttribute("font-weight", "bold");
xAxisTitle.textContent = "Company";
svg.appendChild(xAxisTitle);
var yAxisMarketCapTitle = document.createElementNS(svgNamespace, "text");
yAxisMarketCapTitle.setAttribute("transform", `translate(15, ${padding + chartAreaHeight / 2}) rotate(-90)`);
yAxisMarketCapTitle.setAttribute("text-anchor", "middle");
yAxisMarketCapTitle.setAttribute("font-weight", "bold");
yAxisMarketCapTitle.textContent = "Market Cap (Currency Unit)";
svg.appendChild(yAxisMarketCapTitle);
var yAxisWeightTitle = document.createElementNS(svgNamespace, "text");
yAxisWeightTitle.setAttribute("transform", `translate(${chartWidth – 15}, ${padding + chartAreaHeight / 2}) rotate(-90)`);
yAxisWeightTitle.setAttribute("text-anchor", "middle");
yAxisWeightTitle.setAttribute("font-weight", "bold");
yAxisWeightTitle.textContent = "Index Weight (%)";
svg.appendChild(yAxisWeightTitle);
chartContainer.appendChild(svg); // Append SVG to the canvas element's container
}
// Modify calculateMarketCapIndex to call updateSvgChart instead of Chart.js
function calculateMarketCapIndex() {
var companies = [];
var totalIndexMarketCap = 0;
var totalCompaniesMarketCapSum = 0;
var companyEntries = document.getElementsByClassName('company-entry');
var resultsContainer = document.getElementById('results-container');
var companyDataTableBody = document.querySelector('#companyDataTable tbody');
var isValid = true;
companyDataTableBody.innerHTML = '';
resultsContainer.style.display = 'none';
document.getElementById('primary-result').textContent = '0.00%';
document.getElementById('totalIndexMarketCap').textContent = '0.00';
document.getElementById('totalCompaniesMarketCap').textContent = '0.00';
document.getElementById('numberOfCompanies').textContent = '0';
for (var i = 0; i < companyEntries.length; i++) {
var entry = companyEntries[i];
var companyNameInput = entry.querySelector('input[type="text"]');
var sharesInput = entry.querySelector('input[type="number"][id^="sharesOutstanding"]');
var priceInput = entry.querySelector('input[type="number"][id^="sharePrice"]');
var companyName = companyNameInput ? companyNameInput.value.trim() : `Company ${i + 1}`;
var shares = sharesInput ? parseFloat(sharesInput.value) : NaN;
var price = priceInput ? parseFloat(priceInput.value) : NaN;
var companyNameValid = validateInput(companyNameInput.id, 0, undefined, false);
var sharesValid = validateInput(sharesInput.id, 0, undefined, false);
var priceValid = validateInput(priceInput.id, 0, undefined, false);
if (!companyNameValid || !sharesValid || !priceValid) {
isValid = false;
continue;
}
var marketCap = shares * price;
companies.push({
name: companyName || `Company ${i + 1}`,
shares: shares,
price: price,
marketCap: marketCap
});
totalCompaniesMarketCapSum += marketCap;
}
if (!isValid || companies.length === 0) {
return;
}
var companyWeights = [];
for (var j = 0; j 0 ? (company.marketCap / totalCompaniesMarketCapSum) * 100 : 0;
company.weight = weight;
companyWeights.push(weight);
var row = companyDataTableBody.insertRow();
row.insertCell(0).textContent = company.name;
row.insertCell(1).textContent = company.shares.toLocaleString();
row.insertCell(2).textContent = company.price.toFixed(2);
row.insertCell(3).textContent = company.marketCap.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 2, maximumFractionDigits: 2 });
row.insertCell(4).textContent = weight.toFixed(2);
}
var finalPrimaryResult = (companies.length > 0 && totalCompaniesMarketCapSum > 0) ? 100.00 : 0.00;
document.getElementById('primary-result').textContent = finalPrimaryResult.toFixed(2) + '%';
document.getElementById('totalIndexMarketCap').textContent = totalCompaniesMarketCapSum.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 2, maximumFractionDigits: 2 });
document.getElementById('totalCompaniesMarketCap').textContent = totalCompaniesMarketCapSum.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 2, maximumFractionDigits: 2 });
document.getElementById('numberOfCompanies').textContent = companies.length;
resultsContainer.style.display = 'block';
// Update SVG chart
updateSvgChart(companies.map(c => c.name), companies.map(c => c.marketCap), companyWeights);
}
function resetCalculator() {
companyCounter = 1;
document.getElementById('companyInputsContainer').innerHTML = `
Total number of shares available for this company.
Current trading price per share.
`;
// Clear results and hide container
document.getElementById('results-container').style.display = 'none';
document.getElementById('primary-result').textContent = '0.00%';
document.getElementById('totalIndexMarketCap').textContent = '0.00';
document.getElementById('totalCompaniesMarketCap').textContent = '0.00';
document.getElementById('numberOfCompanies').textContent = '0';
document.querySelector('#companyDataTable tbody').innerHTML = ";
// Clear SVG Chart
var chartContainer = document.getElementById('marketCapChart');
chartContainer.innerHTML = ";
}
function copyResults() {
var resultsContainer = document.getElementById('results-container');
if (resultsContainer.style.display === 'none') {
return; // Don't copy if no results are displayed
}
var primaryResult = document.getElementById('primary-result').textContent;
var totalIndexMarketCap = document.getElementById('totalIndexMarketCap').textContent;
var totalCompaniesMarketCap = document.getElementById('totalCompaniesMarketCap').textContent;
var numberOfCompanies = document.getElementById('numberOfCompanies').textContent;
var companyTable = document.getElementById('companyDataTable');
var companyRows = companyTable.querySelectorAll('tbody tr');
var textToCopy = "Market Cap Weighted Index Calculation Results:\n\n";
textToCopy += `Overall Index Weight (of entered companies): ${primaryResult}\n`;
textToCopy += `Total Index Market Cap: ${totalIndexMarketCap}\n`;
textToCopy += `Number of Companies Included: ${numberOfCompanies}\n\n`;
textToCopy += "Company Breakdown:\n";
textToCopy += "————————————————————\n";
textToCopy += "Company Name | Shares Outstanding | Share Price | Market Cap | Index Weight (%)\n";
textToCopy += "————————————————————\n";
companyRows.forEach(function(row) {
var cells = row.querySelectorAll('td');
textToCopy += `${cells[0].textContent} | ${cells[1].textContent} | ${cells[2].textContent} | ${cells[3].textContent} | ${cells[4].textContent}\n`;
});
textToCopy += "————————————————————\n";
navigator.clipboard.writeText(textToCopy).then(function() {
var copyMessage = document.getElementById('copy-message');
copyMessage.style.display = 'block';
setTimeout(function() {
copyMessage.style.display = 'none';
}, 2000);
}).catch(function(err) {
console.error('Failed to copy text: ', err);
// Fallback for older browsers or if permission denied
var textArea = document.createElement("textarea");
textArea.value = textToCopy;
textArea.style.position = "fixed";
textArea.style.left = "-9999px";
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Fallback: Copying text command was ' + msg);
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
}
document.body.removeChild(textArea);
var copyMessage = document.getElementById('copy-message');
copyMessage.style.display = 'block';
copyMessage.textContent = 'Copied (Fallback)!';
setTimeout(function() {
copyMessage.style.display = 'none';
}, 2000);
});
}
// Initial calculation on load if values are present (optional, usually triggered by button)
// document.addEventListener('DOMContentLoaded', calculateMarketCapIndex);
// Or just ensure sensible defaults are shown
window.onload = function() {
// Optionally run calculation on load if default values exist and are sensible
// calculateMarketCapIndex();
};