NEW YORK and LONDON, March 28, 2013 /PRNewswire/ -- The return of U.S. investors to equities markets and more aggressive investing by non-U.S. investors could drive stock prices higher, even after a four-year rally that has more than doubled prices, according to a recent white paper from the BNY Mellon Investment Strategy & Solutions Group (ISSG). U.S. investors could be reaching an inflection point where they begin returning to equities after years of seeking safer assets and missing the rally that began in March 2009, according to the paper: What if Something Goes Right? Equity Market Risk Signals and the Great Rotation. The report also notes that the non-U.S. investors who have been fueling the bull market have enough buying power to send the prices of stocks in general and growth stocks in particular higher. These non-U.S. equities investors have been concentrating their investments primarily in defensive stocks, the report said. "While stocks have rallied sharply, the gains have been built on a foundation of worry and risk aversion," said Robert Jaeger, senior investment strategist for ISSG and co-author of the report. "These worries are reflected by the valuation premiums that defensive sectors command over growth-oriented sectors. This combination of investor sentiment and valuations could indicate that investors in the U.S. and abroad have substantial potential buying power to acquire growth stocks, even after the big move that we've had." Various sources of concern such as the U.S. fiscal cliff, the possible breakup of the eurozone and slowing growth in China did not stop the rise of equities during late 2012 and early 2013, according to the ISSG report. Still, U.S. investors tended to overweight defensive and dividend-growing sectors while avoiding growth stocks, even when they did move to stocks, the report said. "They are more focused on what can go wrong than what can go right," said Jaeger. "But if things go right, too many investors could miss any continuation of the rally if it develops."