Concern is mounting over another potential vulnerability in the crypto market: Tether, a company whose namesake currency is a linchpin of crypto trading worldwide. Long one of the most scrutinized companies in the industry, Tether is facing heightened pressure from regulators, investors, economists and growing legions of skeptics, who argue it could be another domino to fall in an even bigger crash.

“Tether is really the lifeblood of the crypto ecosystem,” said Hilary Allen, a finance expert at American University. “If it imploded, then the entire facade falls down.”

Tether is the dominant issuer of stablecoins, a type of cryptocurrency pegged to a stable asset like the U.S. dollar. Unlike traditional cryptocurrencies such as Bitcoin and Ether, whose monetary value can fluctuate widely, stablecoins are typically designed to maintain a constant price of $1 and are backed by large reserves of funds or other financial engineering. That consistency allows crypto traders to conduct safe, predictable transactions without relying on banks or other financial gatekeepers.

But many of these coins are stable in name only.