Watch CNBC's full interview with Goldman Sachs' co-head of investment banking

CNBC's "Closing Bell" team discusses global mega deals, the economic recovery, the surge of SPACs, diversity in the workplace and more with Gregg Lemkau, co-head of investment banking at Goldman Sachs. The markets have been incredibly busy. What's been amazing about the M&A market is that back in March, April and May there was no activity, Lemkau says. It was down 85 percent and completely dead. We started to see activity pick up meaningfully in September, he adds.