Stocks that split shares since 2011 have performed about the same as the S&P 500 during the three months since the action, according to data compiled by Bloomberg. The median company rose 6 percent, compared with a 4.5 percent gain for the benchmark gauge.

Past Rallies

Salesforce.com Inc., the largest maker of online customer- management software, rose 2.1 percent in the three months since the April 18 four-for-one split, compared to a 9.6 percent S&P 500 rally. Whole Foods Market Inc., the largest natural-goods grocer in the U.S., added 2.7 percent since distributing one share for each owned on May 30. The S&P 500 is up 1.9 percent since then.

The advance that began in March 2009 is lifting more companies than past rallies, contributing to the increase in stocks trading above $100. A version of the S&P 500 that strips out biases related to market value has gained 220 percent during that stretch, compared with 149 percent in the weighted gauge.

Previous bull markets were narrower, with gains confined to fewer stocks. In the last 50 months of the 1990s technology bubble, the S&P 500 increased 146 percent, almost double the increase in the Equal-Weighted Index, as computer companies such as Microsoft Corp. and Cisco Systems Inc. monopolized the rally.

Trading Brake

In isolation, fewer splits and record prices reduce equity market volume by lowering the number of shares that can be bought and sold for the same amount of money. About 5.67 billion shares of U.S. equities traded hands each day on all U.S. exchanges since June 30, compared to 6.03 billion in the same period last year. At the same time, the value of traded shares climbed to $203 billion a day from $190 billion.

Lower prices attract so-called high-frequency traders who buy and sell hundreds of shares in fractions of a second, attempting to profit from the price disparities. For companies that trade above $100, an average of 1.7 million shares changed hands daily, according to three-month data compiled by Bloomberg. The volume for stocks less than $25 was 11.5 million.

Citigroup Inc. reverse split its stock in May 2011, turning 10 shares into one and bringing the price above $40. CEO Vikram Pandit said part of the reason was to “encourage institutional and other long-only buyers of the stock to invest in our company and also to discourage high-frequency trading that fuels volatility.”

Volume Drop