Investors can’t stop piling more money into stock-market bets. Wall Street is making a killing on it. JPMorgan Chase JPM 1.17%increase; Goldman Sachs GS 1.06%increase; and the other three biggest banks on Wall Street are on pace to have their best trading years ever, after a second-quarter boom in activity. In the past, such gargantuan hauls for trading desks have been a sign of turmoil in the markets. For several banks, the previous record-trading year was 2009, when the market was going haywire.
