Private equity promised an M&A boom this year. The world is still waiting

• Private equity firms are taking longer to return cash to investors and finding it more difficult to raise new funds. The industry could use a long-awaited surge in M&A, and there are signs of optimism when it comes to big money transactions.

Markets reeled in early March as President Donald Trump started his tariff barrage by targeting Canada and Mexico—foreshadowing what was to come on “Liberation Day” the following month. At a conference hosted by Bloomberg in downtown Manhattan...