After a record-breaking 2020, the SPAC market is booming in 2021. In the first three months of 2021, PwC reports that about 300 SPACs have hit the public markets, raising nearly $90 billion in cash, more than all of last year’s record volume. But the high-flying industry could come to a temporary halt. The reason? A potential change in accounting for some SPACs demanded by the SEC.