Mark Johnson, HSBC's global head of foreign exchange trading was arrested on Tuesday night. A former colleague, Stuart Scott, has also been charged.
The two traders are accused by the US Department of Justice (DoJ) of using inside information to profit from a $3.5bn (£2.6bn) currency deal.
HSBC said it did not comment on individual employees or active litigation.
However, a spokesman said the bank was cooperating in the DoJ's ongoing investigation into global currency markets.
Mr Johnson was released on $1m bail following a court hearing on Wednesday.
The US Department of Justice (DoJ) accuses the traders of "front-running".
That is misusing confidential information provided by a client who planned to convert $3.5bn into British pounds.
It is claimed that the two executives bought sterling themselves before handling the order, because they knew that such a large transaction would push up the value of the currency, and allow them to make money.