Morgan Stanley posted a jump in first-quarter trading revenue while Goldman Sachs Group Inc.’s dropped, the first such divergence in two years.

Morgan Stanley on Thursday reported a surprise 9 percent increase in fixed-income trading revenue, the only gain among major Wall Street banks, and had the biggest improvement in equity trading as it overtook its larger rival for the top spot in that business. Goldman Sachs suffered the sharpest decline in equity trading, citing a slump in Japan and emerging markets.