Writes Chris Geidner, in "Exclusive: Justice Alito sold Bud Light stock amidst anti-trans boycott effort/Alito did not respond to questions about the sale, but its timing raises fair questions — particularly in light of other recent ethical questions" (Law Dork).
Why would selling the stock reveal an anti-trans bias? If anything, it reflects a belief that the stock will go down because other people are biased. To participate in the boycott would be to decline to continue to buy Bud Light beer. There's no evidence that Alito was a Bud Light consumer. I googled Does Alito drink beer and I found this 2006 article in the Princeton Alumni Weekly, "A Tiger on the Court: Sam Alito ’72 at Princeton":
