Companies are doing deals at a rapid clip so far in 2021, and some M&A veterans don’t expect the flow to stall out anytime soon.

During the first quarter of 2021, global mergers and acquisitions activity totaled $1.3 trillion, up 94% compared to Q1 of last year, while also booking the highest year-to-date total since 1980, according to a Refinitiv report out this week.

None of that is surprising to Marc Cooper, the CEO of boutique investment bank PJ Solomon. Cooper, who joined the advisory firm in 1999, declares, “It’s as robust a market as I’ve seen in 10 years,” he tells Fortune.

At PJ Solomon, there’s “anecdotal evidence to suggest this forward calendar [year] is out of control,” says Cooper. He hedges that it might not be “apples to apples” because his firm is currently growing in size, but he estimates that “nevertheless, we’ll do 80% of…the full-year revenues we did last year in the first half.”

And M&A is expected to show strong numbers in the latter half of 2021, too, because “you have to have some prospective of what you’re working on now, because these deals take a long time. And if the backlog means anything, it’s going to be a big back half,” argues Cooper.

What’s been driving the frenzy, says Cooper: “Liquidity, liquidity, liquidity.”

Dealmakers are feeling bullish as the U.S. and global economies emerge from the pandemic, suggests Cooper. And with the Biden administration looking to spend trillions of dollars more in stimulus and infrastructure spending later this year (plus a Federal Reserve that is “never going to cut back”), it all becomes “a very conducive environment to do deals,” argues Cooper.

A SPAC ‘shut down’?

One key contributor to the recent M&A boom has been SPACs—which, given the pace of filings this year, still need to get a lot of deals done in the next 24 months, notes Cooper. The vehicles, called special purpose acquisition companies, have seen massive issuance and inflows since 2020. (Meanwhile, SPACs already surpassed all of last year’s issuance in March 2021.) But even as the SPAC boom now begins to wane (lately there haven’t been as many SPAC initial public offering listings versus earlier in the year), Cooper foresees something like a “shutdown,” he says.

“You’ll see a lot of SPACs flaming out; you’ll see some companies not doing so great, and then a year from now you’ll see learnings,” he says.

For now, the “most important thing to keep your eye on” is “the performance of these companies once they de-SPAC,” or merge with a target company. “Right now, you don’t have a whole hell of a lot of performance because the big run-up started last year,” Cooper says. “Let’s give some of these SPACs some time to mature and see where they perform. That’s going to be the issue.”

The Fed fear

Outside of the speculative SPAC space, Wall Streeters continue to wring their hands over whether rising bond yields and the potential for higher inflation will force the Fed to jack up interest rates—dealing a blow to the public and private markets alike.

If rates were to surpass 2% or 3% this year, “valuations will go down, money will become more expensive, all of which will have a negative effect on M&A,” PJ Solomon’s Cooper suggests.

He doesn’t expect rates will rise too rapidly in 2021 but notes the prospect of a sudden Fed move is “a little scary.”

“I don’t know how this unwinds. I don’t know how the Fed stops without us taking on some pain,” says Cooper. “There’s a real uncertain future out there.”