Circle Internet Financial, the company behind the USDC stablecoin, is under investigation by the U.S. securities watchdog. The firm revealed in a recent regulatory filing that the Securities and Exchange Commission (SEC) subpoenaed it in July, although it refused to reveal what the probe was about. Circle is one of the two key companies behind the Centre Consortium, the organization that issues the USD Coin (USDC) stablecoin\u2014with the other being Coinbase. USDC is the second largest stablecoin in the market after Tether, with a $32 billion market cap. Circle is planning on going public via a special-purpose acquisition company (SPAC) deal, merging with Concord Acquisition Corp in a deal that values the firm at $4.5 billion. As part of the move, the company has filed a Form S-4 with the SEC, revealing a probe into the company by the watchdog. \u201cIn July we received an investigative subpoena from the SEC Enforcement Division requesting documents and information regarding certain of our holdings, customer programs, and operations. We are cooperating fully with their investigation,\u201d Circle revealed in its filing. The company has declined to reveal what the investigation is about, claiming it can\u2019t disclose details about an ongoing investigation. However, a spokesperson for the company told Bloomberg, \u201cCircle is cooperating in an ongoing SEC investigation.\u201d However, it\u2019s speculated that the probe is likely on the company\u2019s high-interest yield product. Known as Circle Yield, it\u2019s advertised as a \u201cwell-regulated cryptocurrency yield product.\u201d It\u2019s only available to accredited investors in the U.S. and Sweden, with Circle claiming that the product\u2019s regulated by the Bermuda Monetary Authority. The yield product by Circle is quite similar to Coinbase Lend, a product that\u2019s attracted the interest of the SEC as well, leading to its dismissal before it even launched. However, unlike its Centre Consortium partner, Circle recognized its product as a securities offering, and followed protocols governing such a product. Jeremy Allaire, the company\u2019s founder and CEO told Yahoo, \u201cOur analysis was that this was going to be a security and that we need to offer it as a security.\u201d This is not Circle\u2019s first run-in with regulators. In August, the company paid over $10 million in a settlement with the SEC in relation to Poloniex, its former subsidiary, which was found to have been operating an unregistered digital asset exchange in the United States. Follow\u00a0CoinGeek\u2019s Crypto Crime Cartel\u00a0series, which delves into the stream of groups\u2014a from\u00a0BitMEX\u00a0to\u00a0Binance,\u00a0Bitcoin.com,\u00a0Blockstream,\u00a0ShapeShift,\u00a0Coinbase,\u00a0Ripple and Ethereum\u2014who have co-opted the digital asset revolution and turned the industry into a minefield for na\u00efve (and even experienced) players in the market.