President and CEO of Priceline.com, Jeffery Boyd, gestures as he delivers the keynote address to the Economic Club of Detroit at the Ford Conference Center October 9, 2003 in Dearborn, Michigan. - 

As of this week, Priceline is the first S&P 500 company ever to trade above $1,000 a share.

So far there's no sign the online travel booking company will split its stock to make shares more affordable, but more companies with high-price shares are also letting it ride as the bull market continues.

Think back to before the recession; in 2007 there were 41 stock splits on the S&P. So far this year there've been 10.

"So clearly it's become less popular," says Thomas Chemmanur, a finance professor at Boston College who studies stock splits. "From the fundamentals point of view -- operating performance, earnings and so on -- there is really no effect of stock splits."

That's because the total value of the stock stays the same. Split shares are more affordable for the average Joe, but what if fewer Joes are buying?

"More and more retail investors are gravitating toward mutual funds or Exchange Traded Funds as their vehicle of choice rather than buying individual shares," says Richard Petersen, a Director with S&P Capital IQ. In other words, the actual price of a company's share doesn't matter.

Plus times aren't so tight and high prices are holding. A record number of shares on the S&P 500 are trading above $100, including MasterCard, which has never split its stock, and Apple, whose last split was before the recession.