Global stock-market gains are likely to moderate over the next 12 months after the S&P 500 and other major markets delivered strong returns over the past year. Peter Oppenheimer, Goldman Sachs' chief global equity strategist, expects returns across major regional equity markets to remain mostly in the mid- to high-single digits as investors have already captured substantial gains. Goldman Sachs has also said company earnings and global economic growth should support equities, while warning that valuations had reached historically high levels after the sharp advance.