(Reuters) -Kraken, one of the world's largest cryptocurrency exchanges, said on Thursday it would buy retail futures trading platform NinjaTrader for $1.5 billion, in a deal that would allow it to expand into multiple asset classes and grow its user base. The acquisition comes at a time the crypto industry is optimistic about more relaxed regulation under U.S. President Donald Trump, who courted crypto donors during the election and promised to support the sector. Earlier this month, the U.S. Securities and Exchange Commission dismissed a civil lawsuit accusing Kraken of operating illegally as an unregistered securities exchange.