US banks are sitting on a pile of cash that could turn into billions of dollars of profits. In the coming months, banks are expected to free up tens of billions of dollars in reserves they set aside to cover soured loans-losses that still haven’t materialized a year into a pandemic that shut down swaths of the US economy.In 2020, banks rushed to build up their stockpiles to cover losses on the assumption that consumers and businesses would default on their loan after government stimulus ran out. US banks had $236.6 billion in total reserves in December, according to the Federal Deposit Insurance Corp., almost double their level from before the coronavirus upended the economy and sent unemployment up sharply.Bank executives aren’t so concerned anymore. The economy has outperformed banks’ internal forecasts. Vaccine distribution is ramping up. And a $1.9 trillion stimulus package was signed into law last week. Consumers and businesses, likely have dodged the pandemic’s worst-case financial scenario. Reserves are meant to cover expected losses on loans. They subtract from a bank’s profit when they are put in place and add to it when they are removed.