The UK High Court has approved SABMiller’s (SAB) plan to hold two separate shareholder votes on the AB InBev (ABI) takeover deal, potentially putting the global mega-deal under threat.

The UK-listed brewer announced today that the court had backed its plan that its two largest investors, Colombia’s Santo Domingo family and cigarette maker Altria, should be treated as a separate class of shareholder for the vote to approve the transaction.

SABMiller took the decision to split the vote after other shareholders expressed unhappiness at the cash and shares option being offered to its two largest shareholders compared with the cash only option for other shareholders.

SAB shareholders have protested that the post-Brexit fall in the pound effectively makes the cash/shares option – which has a lengthy lock-in period preventing most ordinary shareholders from taking it up – significantly more valuable than the straight cash offer.

AB InBev upped its final cash offer from £44 per share to £45 per share last month, which was recommended by the SAB board subject to gaining 75% approval from shareholders in a vote excluding the Santo Domingo family and Altria.

The court’s backing of SABMiller’s proposal puts the whole takeover back under threat of collapse as effectively as few as 15% of SAB shareholders could block the deal by voting against it.

The crucial vote is set for 28 September, with the deal expected to be completed on 10 October.