What Happens to the Bid-Ask Spread After a Market Buy Order?

It is impossible to determine the new bid-ask spread without knowing the current state of the limit order book for Stock A. The bid-ask spread is the difference between the highest price a buyer is willing to pay (bid) and the lowest price a seller is willing to accept (ask). A market buy order executes immediately at the best available ask price. Therefore, the new bid-ask spread will depend on how the market buy order affects the existing limit orders at or near the current ask price.