Hunting unicorns used to involve entrapment by a virgin. Now it requires merely the writing of large cheques. Hardly a week passes without a promising tech startup earning a valuation of more than $1 billion from venture capitalists, so becoming (in tech parlance) a unicorn. There are now more than 100 such firms. Nine have been valued at over $10 billion; two—Xiaomi, a Chinese smartphone-maker, and Uber, scourge of taxi drivers the world over—at $40 billion-plus. But doubts about such valuations are growing. Fenwick & West, a law firm, has analysed 37 financing deals. It found that all included protecting investors against losing money—in particular, putting them first in line to get their money back if the company is sold or goes public at a lower price. “Unicorn valuations are not directly comparable to public-company valuations,” the authors conclude. In other words, true unicorns are still rare—even in the magical world of technology.