Apple Inc. has boosted net income to $16.6 billion from $7.25 billion in March 2009. The Cupertino, California-based maker of iPads is projected to grow net income 54% in its fiscal year ending in September, data compiled by Bloomberg show. Apple is set to report second-quarter results on April 20.

Earnings Season

AIG shares have surged 497% since March 9, 2009, while Apple jumped 315% and ConocoPhillips rallied 118%. Alcoa Inc., which rebounded 224%, starts the earnings reporting season on April 11. The New York-based aluminum producer may post a 268% increase in first- quarter net income, according to the average of five analyst estimates compiled by Bloomberg.

The S&P 500 trades for 13.7 times estimated 2011 earnings, compared with an average of 15.7 times reported annual profit since 1900, Shiller data compiled by Bloomberg show.

Earnings for the measure will total $95.21 this year, according to S&P's estimate when adjusted for inflation using the median economist projection for the consumer price index in a Bloomberg survey. If that forecast is met and the 12-month price-earnings multiple climbs to its mean since 1900, the S&P 500 would rise 12% to end December at 1,494, or 4.7% away from its record of 1,565.15 on Oct. 9, 2007.

Analysts' Forecasts

S&P 500 profit has topped analysts' average forecasts eight straight quarters, according to data compiled by Bloomberg. Inflation-adjusted profits for the index will climb 22% in 2011, estimates compiled by S&P and Bloomberg show.

Shiller, whose book "Irrational Exuberance" foreshadowed the end of the 1990s surge in stocks, said in an interview that U.S. equities are "expensive." The S&P 500's cyclically adjusted price-earnings ratio, a valuation measure popularized by Shiller that is calculated by dividing the index's price by the average inflation-adjusted earnings during the past 10 years, is 41% higher than the average since 1900.

"I view current market conditions as a great opportunity to take risk off the table," said Rob Arnott, founder of Research Affiliates LLC, which oversees $75 billion in Newport Beach, California. "When markets are expensive, you're better off letting somebody else bear the risk to pick up that last nickel in front of the steamroller."

Stimulate The Economy

Profits are being inflated by government attempts to stimulate the economy that won't last, and earnings will eventually "mean revert," or fall back toward average levels, according to Arnott, who prefers emerging-market bonds and short-term corporate debt.