GameStop revealed on Tuesday that it pledged nearly all of its Bitcoin as collateral on Coinbase as part of a covered call strategy in January, ending two months of speculation over whether it had sold the coins. In a 10-K annual report to the Securities and Exchange Commission on Tuesday, the video game retailer revealed it pledged 4,709 Bitcoin (BTC), nearly all of its Bitcoin, as collateral under an agreement with Coinbase Credit, using the position to sell covered call options. The SEC filing clears speculation from January that GameStop…