The breadth of this rally is also a consequence of investors favoring industries where earnings are less likely to plummet should the economy weaken. Health-care and household product companies posted the biggest gains in the S&P 500 last quarter, at 15 percent and 14 percent. So-called defensive shares have an average dividend yield of 2.4 percent, compared with 1.7 percent for cyclical stocks, data compiled by Bloomberg show.

Advances in companies that fund managers buy when they are expecting gains to slow have resulted in a smaller spread between the market’s leaders and laggards compared with the dot- com era. During the 1990s, computer makers and software designers surged 587 percent, more than four times as much as any other industry in the S&P 500 and at least 31 times more than utilities and household-product makers. Since March 2009, consumer discretionary shares have jumped 258 percent, or about three times as much as the worst-performing industries.

Yahoo, Dell

Yahoo! Inc., the search engine operator, posted the biggest gain in the last 50 months of the 1990s rally, surging 180-fold, while personal-computer maker Dell Inc. rose about 7,000 percent. The biggest gains since March 2009 are Regeneron in Tarrytown, New York, at 2,106 percent, Parsippany, New Jersey- based Wyndham at 1,986 percent, and television network CBS Corp., up 1,445 percent.

Eighteen stocks increased by more than 1,000 percent during the last 50 months of the 1990s rally, twice as many as now. With fewer companies posting returns of that size, individual investors have yet to return to stocks, according to Nick Sargen, who oversees almost $45 billion as chief investment officer at Fort Washington Investment Advisors in Cincinnati.

“The retail investors are more momentum-based, so they don’t go buy names because they’re cheap, they say look, that stock’s on a tear, I want some of that,” Sargen said in a May 8 phone interview. “That’s what was happening in the 1990s. It was a momentum driven market, and the thing was it was a good call for five years, so you did OK, until you didn’t,” he said.

“This just hasn’t been a momentum-driven market today,” Sargen said. “Retail investors have just missed the rally and they’re only now starting to become converts.”

Bond Comparisons

Mutual funds owning bonds have received more than four times as much money as those owning U.S. stocks in 2013, data from Washington-based Investment Company Institute show. Investors withdrew almost $400 billion from American equity funds over the last four years and added more than $1 trillion to bonds.

Treasuries have underperformed stocks during the bull market, losing 0.1 percent this year, compared with the S&P 500’s 15 percent, data from Bank of America Merrill Lynch and Bloomberg show. While bonds beat stocks in 2011, equities outperformed in 2010 and 2012, giving stock investors a total return about nine times as big as bondholders since March 2009.