(Some Fortune Crypto pricing data is provided by Binance.)

The price of tokens tied to some of the best known blockchains plummeted on Friday days after the Securities and Exchange Commission declared them to be securities in complaints filed against Bitcoin and Ethereum experienced only minor dips, other well-known crypto projects took a beating.

As of Sunday evening, the price of Solana's SOL token was down nearly 30% over seven days, while Polygon's MATIC token and Cardano's ADA were down 28% and 29.5%, respectively, over the same period.

While crypto prices slumped across the board following the SEC complaints, which dropped last Monday and Tuesday, it was only on Friday that markets experienced a massive sell-off.

The cause of Friday's plunge appears to be a decision by some of the biggest crypto market makers and trading firms to dump their holdings. A Coindesk report pointed to tweets from the analytics firm LookOnChain, which cited blockchain data to say wallets tied to Cumberland, Jump Trading and Robinhood had off-loaded a large volume of tokens to exchanges.

These firms' large holdings, combined with an illiquid trading environment following the SEC declaration, likely led to an especially steep drop in prices. Meanwhile, Robinhood on Friday announced it would delist Solana, Cardano, and Polygon from its exchange as of June 27—another likely blow to their value.

Solana and Cardano are so-called layer-1 blockchains, which aspire to challenge Ethereum, while Polygon is a side-chain that helps process Ethereum transactions more efficiently. While they took the biggest price hit, other well-known blockchains also experienced a big blow in the wake of the SEC complaints.

The seven-day price for tokens tied Filecoin and Internet Computer—both of which were also labelled as securities by the SEC—were down 26% and 24%, respectively, on Sunday. Meanwhile, a number of well-known older projects, notably Litecoin and Dogecoin, were not labelled as securities and have fallen by around 15%.

The crypto industry has long decried what it claims has been a lack of guidance from the SEC when it comes to determining which blockchain tokens are securities. The issue is the subject of a closely watched legal battle between the agency and Ripple, which is associated to the XRP token. A decision is expected as soon as this summer.

Bitcoin, which is down 4% over the past week, is the only token that the SEC has stated not to be a security. Ethereum, whose legal status is unclear, is down 7%. The two tokens are by far the biggest cryptocurrencies by market cap.