Microsoft's dollar volume towers over the other 29 Dow stocks.

Microsoft (NASDAQ:MSFT) is not the largest company on the Dow Jones Industrial Average (DJINDICES:^DJI) ExxonMobil (NYSE:XOM) holds that crown with a $402 billion market cap, relegating Microsoft's $287 billion cap to second place. Eleven Dow components sport higher annual revenues than Microsoft's $80.4 billion, led by Exxon at $398 billion and Wal-Mart (NYSE:WMT) at $475 billion. The software giant is not the Dow's most profitable company, either, or its fastest-growing member.

But there's one place where neither Wal-Mart nor Exxon, or any other Dow member for that matter, can touch Microsoft. It's the Dow's most popular stock, judging by the average daily dollar volumes traded.

A total of $1.8 billion of Microsoft stock changes hands every day, leaving Exxon far behind in second place with a $1.2 billion daily dollar volume. Wal-Mart is nowhere near the top, sitting in the middle of the 30 Dow components with just $614 million of daily trading action to its name.

In fact, Microsoft shifts more dollar volume every day than nearly any other stock on the market. Apple (NASDAQ:AAPL) rules the roost with a totally unchallenged $6.7 billion daily action. Google also runs in front at $1.8 billion -- a rounding error ahead of Microsoft.

So what makes Microsoft so special? Why should investors care about daily trading volumes? I can think of at least two important reasons:

  • With billion-dollar daily trading volumes, Microsoft is one of the market's most liquid stocks. Fools should still prefer setting their price for every trade with limit orders rather than blindly accepting whatever your broker sees as the current market price, but if you're ever going to use a market order, Microsoft and Apple would be fairly safe bets.

  • In the world of open-source software development, you'll find Linus' Law: "Given enough eyeballs, all bugs are shallow." In other words, let a ton of smart people examine your code, and every problem will soon be apparent -- and fixed. The same idea applies to the stock market; investors just know the idea as the "efficient markets" hypothesis or "the wisdom of crowds." You're more likely to get a fair price on stocks that are evaluated by thousands of investors every day. Ergo, Microsoft and Google are probably closer to fair value than most stocks at any given moment.

I'm not saying that Wal-Mart or Exxon are speculative, or that the high volumes of Apple, Google, and Microsoft somehow makes them safer investments. Even the least popular Dow stocks see nearly $200 million in daily trading, after all. We're hardly talking about microvolume penny stocks here. But the safety in numbers around Wal-Mart's shares applies more strongly to the higher-volume tickers -- and the popularity title is a rare feather in Microsoft's hat.

Nobody ever complained about being No. 1, right?