The stock has risen more than 30 percent since the start of December, and its estimate-topping earnings late last month added fuel to its recent gains.

The shares touched a historic high of $526.29 on Wednesday, up more than 3 percent on the day, before closing down 2.3 percent at $497.67.

Here's a look at Apple's massive presence in the U.S. stock market.

* Apple's market capitalization is about $464 billion, more than the combined market cap of Google Inc ($197 billion) and Microsoft Corp ($252 billion)

* The earnings growth rate for the S&P 500 in last year's fourth quarter is 8.9 percent. Excluding Apple, the rate drops to 5.8 percent.

* The current estimated growth rate for the S&P 500 in the first quarter of 2012 is 2.25 percent, but without Apple it falls to 0.99 percent.

* Apple's median stock price target from Wall Street is $600, about 20 percent higher than its current price. The highest targets among the 57 analysts that cover the company are $700 from Hudson Square research and $670 from Piper Jaffray. Thomson Reuters StarMine's calculation of the stock's intrinsic value is now $637.10.

* So far in 2012, Apple's market cap has risen about $86 billion, from a price gain of 22.9 percent.

* Apple accounted for 9 percent of flows in the options market on Wednesday, with a total of 1.77 million contracts traded, according to Trade Alert. That was a record for contracts traded, exceeding the previous daily record of 1.3 million contracts set on February 9.

* The stock has had two down years in the last decade: 2002 and 2008. Its largest yearly percentage change since 1980 was 212 percent in 1998. The largest decline was 71 percent in 2000.

* In terms of price, the largest yearly change was $125.38 per share, in 2009. So far this year the stock is up $92.67.

* Apple is currently 16.5 percent of the Nasdaq 100 <.NDX>. When its weighting tipped over 20 percent last year, Nasdaq OMX rebalanced the index and left Apple's participation at just above 12 percent.

(Reporting by Rodrigo Campos and Caroline Valetkevitch; Editing by Padraic Cassidy)