If a buyout is announced the price of the stock (assuming it is a nice premium to current price) will most likely rocket to the price very quickly on the open market. Buyouts do not happen instantly, a date will be announced of when the vote to say yay or nay to the offer would be set for current stockholders. You can buy or sell stock at any time after the announcement.

Usually between announcement and deal completion the price hangs around the buyout price until the deal is completed on the specified date. You can hang on or sell at any point. If the deal were to include stock in the acquirer, you may want to hang on as you would still be part of the leronlimab saga, in an all cash deal you'll end up selling all your shares whether you wanted to or not.

Hope that answers your question.