I've been checking historical prices for some stocks at Google finance and Yahoo finance but something doesn't quite add up.

Taking stock splits into account, Google finance "says" that Microsoft's highest intraday high was 59.97 USD, which would mean that the company hit a market capitalization of 503 billion USD in 30 December, 1999:

US$59.97 * 8,390.77 shares = US$503,194.477 million

Yahoo finance has a 119.94 on the same day (which matches Google's value of 59.97 after the 2:1 split), but they say the adjusted value is 45.57 for the close (117.62), which would mean that the adjusted value would make it's market cap value even lower.

Some other sources point that Microsoft hit US$604 billion market cap once. Even Wikipedia shows the market cap for Microsoft was US$586 billion in 31 March, 2000 citing Financial Times as it's source.

My question is: What am I missing here?

3 Answers 3


In common with many companies, Microsoft has been engaging in share buyback programmes, where it buys its own shares in the market and then cancels them. It's often a more tax-efficient way to distribute profits to the shareholders than paying a dividend. So there were more Microsoft shares in circulation in 1999 than there are now. See here for information.

  • 1
    yes there were a few times where MS dropped very low and the company took advantage to institute buy backs. The number may also be Inflation Adjusted.
    – user4127
    Commented Feb 29, 2012 at 21:00

Adjustments can be for splits as well as for dividends. From Investopedia.com:

Historical prices stored on some public websites, such as Yahoo! Finance, also adjust the past prices of the stock downward by the dividend amount.

Thus, that could also be a possible factor in looking at the old prices.


Everything would depend on whether the calculation is being done using the company's all-time high intraday trading price or all-time high closing price. Further, I've seen calculations using non-public pricing data, such as bid-offer numbers from market makers, although this wouldn't be kosher.
The likelihood is that you're seeing numbers that were calculated using different points in time. For the record, I think Apple has overtaken Microsoft's all-time highest market cap with a figure somewhere north of $700 billion (nominal). Here's an interesting article link on the subject of highest-ever valuations:

comparison of highest market caps ever

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .