At the same time, investors are concerned that the money was made via means that are nearing depletion. Earnings have grown at an annual rate of 14 percent since 2009, about three times faster than sales, as companies cut costs. Rather than investing to meet demand that might not come, executives juiced returns by spending near record amounts on buybacks.

‘Big Disconnect’

“You can’t do a whole lot more cost cutting and you can’t buy back a whole lot more stock,” David Lafferty, the chief market strategist for Natixis Global Asset Management in Boston, said by phone. His firm manages about $930 billion. “The big disconnect where companies have been able to grow their earnings significantly faster than top-line revenue growth is coming to an end.”

More than $11 trillion has been added to S&P 500 stock values since the bull market began. Over the same period, GDP rose 0.9 percent a quarter amid the weakest recovery since 1947, data compiled by Bloomberg show. The 68-month advance in stocks is unique among 16 bull markets since 1938 in that it occurred without a single year of GDP growth above 3 percent.

One hazard for investors is shown in valuation gauges tied to revenue. Since global equities bottomed in March 2009, the S&P 500’s price-sales ratio has expanded about three times as fast as price-earnings, rising from 0.7 to 1.8 last month, the highest level in more than a decade.

‘Fully Rational’

Stock volatility spurred partly by international concerns may be increasing but the influence of foreign markets is a reason profits have been able to outrun American GDP, according to Stanley Nabi, vice chairman at Silvercrest Asset Management Group in New York. S&P 500 companies get 46.3 percent of sales overseas, according to data from S&P.

“They’re accounted for in the S&P earnings, but they’re not accounted for in the GDP,” Nabi said by phone. Silvercrest oversees about $16 billion. “Profits have risen ahead of nominal growth. It’s fully rational.”

Growth in earnings isn’t poised to end, according to analysts, who say income among S&P 500 companies will rise at an average rate of about 9 percent through 2016, estimates compiled by Bloomberg show. Economic growth has strengthened in the past year, with GDP expanding at an annualized rate of 3.5 percent or more in three of the last four quarters.

3% GDP

GDP probably rose 3 percent in the third quarter and will hold around that level for another two years, according to the median estimates from more than 80 economists surveyed by Bloomberg. Economists predict employers will add 228,000 jobs to payrolls in October after a 248,000 increase in September.

Too much growth is the last thing the economy needs anyway because it may prompt the Fed to raise interest rates sooner than expected, according to Tim Rudderow, chief investment officer at Mount Lucas Management LP in Newtown, Pennsylvania.