Goldman says an under-the-radar driver is signaling further upside in stocks -- one not driven by retail investors

"Investment flows are an important driver of equity returns," according to Goldman Sachs, and right now they're signaling further upside ahead for the stock market. In a note published on Thursday, Goldman went under the hood of the stock market and analyzed the impact fund flows, or the actual trading of securities, had on security prices. The firm found that fund flows can have a sizable impact on market prices if liquidity is especially low, and not so much if liquidity is high. Additionally,...