BlockFi Inc., a crypto-lending startup, mistakenly sent some users Bitcoin as part of a promotion and is working on reversing it.The company made what it called incorrect promo payouts in Bitcoin instead of U.S. dollars to certain customers. Though BlockFi worked on reversing them, a number of recipients withdrew the coins before the company could backpedal. The firm's exposure is around $10 million, though that amount is decreasing as more users return the coins, said Zac Prince, co-founder and chief executive officer of BlockFi."BlockFi "The issue that caused the withdrawals was fixed and incremental safeguards have been developed to prevent any similar issue in the future."The Though it's down significantly this week, each coin is trading around $34,000 Wednesday.Last week, BlockFi tweeted that some promotion participants "may see an inaccurate bonus payment displayed in their transaction history."Meanwhile, It's been in the limelight as it's grown in recent months amid a crypto-market rally that's being unwound this week.Read more: Lending Bitcoin to Earn 6% Comes With Risk You Won't Get at BankThe crypto firm's snafu is reminiscent of Citigroup Inc.'s $500 million blunder last summer when it accidentally sent payments to a group of lenders."As a stand-alone, it was just a glitch," Mike Loukas, chief executive officer at TrueMark Investments, said of BlockFi. "We see it with banks all the time in dollars.