Market capitalization—calculated by multiplying share price by the number of shares outstanding—is just one measure of a company’s value, and one that often says more about short-term sentiment on Wall Street than a company’s long-term prospects.

But Steve Jobs was reportedly obsessed with his market cap.

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The story comes from Bruce Upbin, who runs Forbes Media’s 140-person technology team. Back in 2009, according to Upbin, there was a move afoot to simplify the iPhone’s built-in Stock app.

In the original version, you could tap once to see a company’s stock price, a second time to see the percentage change, and third time to see the market cap.

The engineer working on Stock 3.0 designed a new version that would only toggle between price and percentage change. But the revision made him nervous, so he ran the idea up Cupertino’s chain of command.

Word came back down, according to Upbin, that, no, the third tap showing market cap would stay.

“Why? Steve wanted it that way. Why? Because Apple’s market cap was inching ever closer to that of his old rival Microsoft. Everyone was talking about when Apple would overtake Microsoft in value, the ultimate financial measure of corporate success. Steve wanted to quickly keep track on his phone of AAPL vs. MSFT. The third tap was to be left alone.”

Apple overtook Microsoft (MSFT) later that year. And now Google (GOOG) has overtaken Apple (AAPL).

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Steve Jobs would not have been happy.