One of Wall Street’s most closely watched equity strategists is sounding an alarm: The stock market is exhibiting some of the same dangerous characteristics it did in the run-up to the Global Financial Crisis, and a correction could be imminent. And warnings from Peter Oppenheimer, Goldman Sachs’ chief global equity strategist, carry particular weight—because his contrarian calls have a strong track record. In a research note published Wednesday, Oppenheimer warned equity risk premia—a measure of how mu ...