By Douwe Miedema WASHINGTON (Reuters) – TeraExchange on Friday launched a swap based on the bitcoin virtual currency, becoming the first to receive approval from a U.S. federal regulator for a financial product based on the budding technology. The derivative allows clients to protect the value of their bitcoin holdings by locking in a dollar value, offering an insurance against the astronomical price swings that have plagued the computer-generated currency. For a merchant to take bitcoin, there wasnt until this product a regulated way for them to put on a hedge to manage the risk … …