The Dow Jones industrial average rose, closing above 15,000 for a second day after breaching the landmark level for the first time Tuesday.
On Wednesday, a day without any major economic releases, investors focused on company earnings as reporting for the first quarter draws to a close. Although earnings growth has slowed from last quarter, profits are at record levels and projected to rise throughout the year.
The Dow closed up 48.92 points, or 0.3 percent, at 15,105.12. The index is 15.3 percent higher for the year. The S&P 500 index was 6.73 points higher, or 0.4 percent, at 1,632.69, extending its advance for 2013 to 14.5 percent.
Internet company AOL plunged as its subscription revenue fell, and hamburger chain Wendy's slumped after it reported revenue that fell short of Wall Street's expectations. On the positive side, high-end grocer Whole Foods and the video game publisher Electronic Arts rose sharply after predicting full-year profits that were higher than analysts were expecting.
Scott Wren, a senior equity strategist at Wells Fargo Advisors, predicted more gains in the short term, but he also said a pullback was likely at some point because the rise in the market is beginning to overstate the improvement in the economy.
"We're still going to keep grinding higher," Wren said. But, he added: "I do think the market is ahead of itself."
Stocks have defied predictions that a sell-off would follow the spring surge as signs emerged that growth could be set for a slowdown. Both the Dow and the Standard & Poor's 500 index have gained every month of the year and are trading at record highs.
On Wednesday, AOL plunged $3.68, or 8.9 percent, to $37.74 after the company reported earnings that fell short of the forecasts of Wall Street analysts who follow the stock. Subscription revenue fell 9 percent.
Wendy's fell 34 cents, or 5.6 percent, to $5.78 after it reported a 2 percent rise in revenue to $603.7 million, short of the $615 million forecast of analysts.
Materials and information technology companies gained the most of the 10 industry groups in the S&P 500 index, rising 0.9 percent and 0.8 percent respectively. The two industry groups have surged in the last month and are finding favor with investors after lagging the index for the first three months of the year.
That suggests that investors are moving from the so-called defensive stocks — those which offer good dividends and can grow regardless of the state of the economy — into industries that will benefit more if the economy accelerates. Gains for the year so far have been led by health care stocks, which have advanced 19 percent, compared with 8 percent for technology companies.
"We're seeing some sector rotation," said Chris Bertelsen, the Chief Investment Officer of Global Financial Private Capital. Defensive stocks "have had a huge run this year ... I think you are seeing some change of attitude in the market."
About 90 percent of companies in the S&P 500 index have reported their earnings for the first quarter.
Financial analysts predict that earnings will end up rising 5.1 percent versus the same period a year ago, according to S&P Capital IQ. Although that's slower growth than the 7.7 percent growth of the previous quarter, they are expected to grow 12 percent by the fourth quarter of 2013.
Whole Foods climbed $9.39, or 10.1 percent, to $102.19 after the natural foods store chain said its fiscal second-quarter net income rose 20 percent. The company also raised its profit forecast for the full year.
Electronic Arts, which makes the Madden Football games and SimCity, jumped $3.15, or 17.1 percent, to $21.56 after it projected profits for the current fiscal year that were higher than analysts were expecting.
Freight transporter C.H. Robinson Worldwide was the biggest decliner in the S&P 500 index, falling $4.30, or 7 percent, to $57.26 after the company said that its profit margins were being squeezed.
In government bond trading, the yield on the 10-year Treasury note was little changed at 1.77 percent. The yield has climbed from 1.63, its lowest of the year, last week after a surprisingly strong employment report Friday.
In commodities trading, the price of crude oil rose $1, or 1 percent, to $96.62 a barrel and gold climbed $24.90, or 1.7 percent, to $1,473.70 an ounce.
The dollar fell against the euro and ended the day higher against the yen.