The Winklevoss twins’ Gemini exchange now has $30 billion worth of cryptocurrencies under custody as competition heats up among top U.S. exchanges.In a May 11 announcement, the exchange attributed much of the growth this year to strong demand from institutional clients: “Tracking with the impressive growth of the crypto market this year and increased participation from institutional investors, we have more than tripled our crypto under custody since the beginning of 2021.”Gemini works with large asset managers including BlockFi, Blockchange, CoinList, CI Global Asset Management, DAiM, BTG Pactual, Caruso, Eaglebrook Advisors, and WealthSimple.The New York-based company was founded in 2014 by Cameron and Tyler Winklevoss. In the lead up to rival exchange Coinbase’s April 14 direct listing on the Nasdaq, the pair told Bloomberg they were “considering” taking Gemini public too. If Gemini or another large exchange were to be listed publicly, it could significantly impact Coinbase’s share price — which has fallen from $328.28 on its first day of trading to $288.46 currently. Is Coinbase over-valued?Veteran Wall Street analyst and New Constructs CEO, David Trainer, said in a note to clients on Tuesday that he expects Coinbase’s share price to decline to $100 or even lower due to increasing competition. Trainer suggested that Coinbase is currently overvalued, noting its current valuation implies it will exceed the combined annual revenue of Intercontinental Exchange and Nasdaq.”Investors should expect the stock to continue to underperform, as shares could fall to $100 or less as it becomes clear the company is unlikely to meet the future profit expectations baked into the stock price.”Coinbase is expected to report first quarter earnings of $3.07 per share on revenue of $1.82 billion on Thursday. Trainer said that even if it exceeded expectations, this would only attract more competitors and drive down future revenues.”Coinbase will likely not be able to sustain blowout earnings going forward as competition enters the market,” he said. In April, Trainer warned the mooted $100B valuation for Coinbase was far too high due to stiffening competition from Gemini, Bitstamp, Kraken and Binance.Figures released in March indicated Coinbase Custody had more than $90B assets under custody by the end of 2020.