Some big-name initial public offerings last year were panned for not having a profitable business. Yet more than a quarter of the offerings were of companies with no business at all — by design.

These were special purpose acquisition companies, or SPACs, also known as “blank-cheque companies.” Their goal is to raise money from public and private investors and then identify an acquisition target and buy it, typically within two years. SPACs raised $13.6bn in 59 IPOs last year.