With Europe’s debt crisis and sluggish U.S. economic growth roiling financial markets, U.S. stock strategists are beginning to lower their predictions for the market.

Strategists on average expect the Standard & Poor’s 500 Index to end the year at 1309, according to Birinyi Associates, The Wall Street Journal reports. That represents an increase of 8.7 percent from Monday’s close.

At the beginning of the year, strategists forecast a rise of 8.5 percent for all of 2011, which would leave the index at 1365.

NYSE traders (Getty Images photo)

"At the beginning of the year, everyone was tripping over themselves to raise their S&P 500 targets, and now it's the opposite," said Scott Migliori, chief investment officer for money manager RCM.

Last week Goldman Sachs cut its year-end prediction for the S&P 500 to 1250 from 1400 previously, Wells Fargo cut to 1250 from 1390, and Citigroup cut to 1325 from 1400.

Morgan Stanley’s chief U.S. equity strategist, Adam Parker, argues that other strategists are still too bullish. He sees the S&P 500 ending the year at 1238. U.S. and European fiscal woes represent a major problem, and China’s economy could slow suddenly, he tells The Journal.

Not everyone has turned bearish on stocks. John Bogle, founder of the Vanguard Group, says investors should buy and hold equities in anticipation of 7 percent annual returns in coming years.

"That would mean you’ve doubled your money in the decade," Bogle tells CNBC.