Douglas Ellenoff credits the boom to the erasure of stigma. With nearly 250 blank-check companies launched last year, 2020 may have been "the year of the SPAC," according to a list of commentators too long to count. But the veteran dealmaker and founding partner at New York boutique Ellenoff Grossman & Schole insists the explosion didn't happen overnight.

Dating back to the mid-1990s, Ellenoff and a select group of other practitioners began advising the handful of players who were launching the first special purpose acquisition companies. Just like in today's boom market, with capital in hand after their initial public offering, these entities would snap up a privately held business and take it public, a process commonly, but inelegantly called de-SPAC-ing. But in Ellenoff's telling, there were issues with the rules back then that created unease among both regulators and the business community, prompting a first round of tinkering that included increasing disclosure requirements.