General Question

sferik's avatar

Is there a website that will generate a single-line chart, graphing the performance of a collection of stocks over time?

Asked by sferik (6121points) November 18th, 2009

Whenever I enter multiple stock symbols into Google Finance or Yahoo Finance, I get a chart that contrasts the companies against each other. I’m looking for a similar chart that shows the combined performance of the companies. For example, an index that consists only of AAPL, GOOG, AMZN, NFLX, and TIVO, graphed as a single line over time.

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6 Answers

virtualist's avatar

That would just the sum value of 1 share of each stock plotted versus time. You could normalize it to the ‘index value’ at a particular time if you wished.

I need to think on whether there is a ‘freeware’ site that would do that for you. Maybe Marketwatch with a free registration and Portfolio Personal Index Sferik #1. lol

RareDenver's avatar

Why not just just do a price history table for each stock, copy them into Excel and plot the graph yourself, the feeling of achievement will bring on an enormous sense of well being.

srmorgan's avatar

The problem you are going to have is setting a benchmark and then assigned a “weight’ to each individual stock. For example if AAPL sells at $10/Share and GOOG sells at $30/share, how do assign values as part of the valuation. Is GOOG always going to be 75% of the value of the portfolio?

This is how the Dow-Jones index works. Each of the 30 stocks has a relative weighting which traces back to the original weight of each stock in the original average as calculated in what, 1892?

You could chart the aggregate value of your portfolio every day using the change is total value or the change in % of value without too much trouble and I think Yahoo finance allows you to set up a portfolio with total value by stock (say, 1000 of AAPL = $10,000) so that you can track the sums daily.

You also have to consider what happens if you have a stock dividend declared or you purchase 100 more shares of GOOG or sell the same, how would that affect your calculations?

I would think that something like Microsoft Money would have this covered. Check around for existing software before trying to create this from scratch.


sferik's avatar

I’d prefer a capitalization-weighted index, which should take care of fluctuation in share price. I’ve set up portfolios in Google Finance, but they don’t provide charts with aggregate values.

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