Cryptocurrency custodian company BitGo Holdings said on Monday that it has secretly filed for an IPO amid a wave of optimism in the digital asset market. Founded in 2013, BitGo is one of the largest cryptocurrency custodians in the United States, storing and protecting digital assets for clients. The crypto industry's market capitalization has climbed to $4 trillion, and Bitcoin recently hit an all-time high, breaching the $120,000 mark. Matt Kennedy, senior strategist at Renaissance Capital, sa...