Blockchain hours and market hours are different
Solana transactions can be submitted outside the regular U.S. stock-market session. That does not mean BRK-B is trading on its exchange at the same moment. BRK.Bx references that share through a separate tokenized product, so the token's on-chain trading conditions can diverge from a brokerage order in BRK-B.
When the underlying market is shut, the most recent close may be old information. News can change expectations before the next market open. On-chain liquidity providers may widen spreads, reduce inventory or stop quoting. The practical question is whether there is an executable BRK.Bx route for your amount at an acceptable total cost, not whether the token is technically transferable 24/7.
A useful after-hours checklist
Compare the swap's input and output, price impact, slippage setting and transaction fee. Check when the price snapshot was taken. Confirm that the output mint is Xs6B6zawENwAbWVi7w92rjazLuAr5Az59qgWKcNb45x; symbols alone are not reliable identity. A failed or expired route is a liquidity or execution issue, not evidence that BRK-B's exchange itself was open.
The xStocks product documentation describes the token mechanism. Open the BRK.Bx asset profile for a wallet preview and dated snapshot. This page explains market structure, not a prediction about the next trading session.