Two law professors are aiming at high-profile targets, filing suits that question the legality of a specific type of special-purpose acquisition company. Among them are billionaire William Ackman’s $4bn Pershing Square Tontine Holdings, Go Acquisition Corp, co-founded by veteran entrepreneur Noam Gottesman, and E.Merge Technology Acquisition Corp.

Another line of legal attack is more typical, focusing on Spacs whose shares suffer big falls. These are targeting once-hot companies such as electric truck maker Nikola Corp, which class-action suits claim defrauded investors.