(Reuters) -Coinbase, the largest publicly traded cryptocurrency exchange, said on Thursday it will buy derivatives exchange Deribit in a $2.9 billion deal to expand into the crypto options markets. The move underscores a push by crypto firms to widen their institutional investor base, while also catering to retail traders who are becoming more sophisticated. The Deribit acquisition gives Coinbase "a foothold in non-U.S. markets, especially Asia and Europe, where leverage trading is more prevalent," said Bo Pei, analyst at US Tiger Securities.