Supermarkets, bank branches, best-selling books, barrels of oil — these are just a few of the markets that have vexed competition lawyers and judges over the decades. The battle for US media empire Warner Bros Discovery will pose a whole new set of questions — with no easy answers — about the way households parcel out their TV spending and their brain space.

Netflix’s bid for WBD was trumped on Monday by a rival cash offer from Paramount Skydance. The interloper contends, in support of its offer, that a Netflix merger would trigger a lengthy and possibly unsuccessful antitrust review. The logic is persuasive. George Mason University law professor John Yun cites data showing Netflix and WBD have 31 per cent of streaming subscriptions and account for 35 per cent of hours watched.

But there are other ways to slice the cake. In antitrust probes, identifying the “relevant market” is critical, and contentious. Include Google’s YouTube as a streaming rival, and Netflix and WBD fall to just 20 per cent of viewing time, according to Nielsen. Include all TV, and they’re just 9.3 per cent. Expect lawyers to home in on the definition that best suits their case.