But shockingly, even at $323 billion, Apple still looks cheap.
After all, the company still sports a tiny 13-times forward earnings multiple.
In a normal economic expansion, well-regarded growth stocks earn forward multiples of at least 20-times, and often more like 50-times. Using the average 2012 earnings estimate for Apple, the 20-times multiple would put the stock at $536 by the end of the year, up from $350 now.
That looks reasonable, though this assumes that the company does not beat estimates - which it does regularly - and does nothing with its massive cash hoard, which seems unlikely.
And if you subtract out the company's incredibly large cash hoard of $27 billion - which alone is bigger than the combined market cap of the10 smallest companies in the Standard & Poor's 500 Index - it looks even cheaper.
Still, investors continue to treat Apple as if it will never make another successful product. They act like it's about to have its lunch stolen by bullies, or blow its cash for the most amazing company picnic of all time instead of putting it to productive use. And they act as if all of the company's success to this point will suddenly vanish when Steve Jobs finally retires for good.
Some of these concerns are valid on some level, but none are truly likely to undermine Apple's stock in the long term.
I've recommended Apple stock on several occasions over the past decade, and I've been saying for three years that 13-times forward earnings is too cheap for a company with Apple's level of accomplishment. One day, investors will finally feel as if they can dream a little and at least get the multiple up again to where it truly belongs in the 15x - 17x range.
I mention this because Apple has been one of the leaders of this bull cycle, so its fortunes matter to all investors. Apple is trading about $15 under its all-time high, but has jumped about 3% since releasing its fiscal second-quarter report April 20. The new buying intensity it has attracted could help Apple lead the whole S&P 500 back toward new highs.
The key element to keep in mind with Apple is its cheapness, even at $350. In a normal, fully engaged bull market, it could trade at double this value without making one dollar more simply because people will become more optimistic and more willing to bet that its growth will continue.
As long as we see a provably great company like Apple remain undervalued we can feel confident that the bull market that began in the chaos of March 2009 is still going strong.