Iron Finance: When TITAN Went From $64 to Zero in Hours

On 13 June 2021 Mark Cuban, the billionaire owner of the Dallas Mavericks and a star of the investment show Shark Tank, wrote a blog post about a crypto project he was making money from. He had put his own funds to work in a trading pool for a token called TITAN, and the fees and rewards were running at about 206% a year. Three days later TITAN was worth nothing. "I got hit like everyone else," Cuban wrote on Twitter.

TITAN belonged to Iron Finance, a project run by anonymous developers on Polygon, a cheaper and faster network that runs alongside Ethereum. On 15 June 2021 people had about $2.3 billion deposited in Iron Finance, according to the tracking site DefiLlama. Two days later it was about $300 million. TITAN had risen from almost nothing to around $64 in a few weeks. During 16 June it fell to a tiny fraction of a cent.

Nobody hacked it and nobody ran off with the money. Iron Finance's own post-mortem called it "the world's first large-scale crypto bank run". But the design did to its users what a rug pull would have done, and eleven months later the same design destroyed $40 billion.

A dollar backed by its own shares

At the centre was IRON, a stablecoin: a token meant to be worth exactly one US dollar, like a casino chip that can always be cashed at the cage for a dollar. Most stablecoins try to keep a real dollar, or a Treasury bill, in reserve for every token. IRON kept only part of one. It was copied from Frax, an earlier design built on the same idea of a partly backed dollar.

The rules were simple. At the time, to create one IRON, a user handed over 75 cents of USDC, a dollar token backed by cash, plus 25 cents' worth of TITAN, which was destroyed. To cash one IRON back in, the user got 75 cents of USDC and 25 cents' worth of brand-new TITAN, printed on the spot. In stock market terms, it was a bank that held three quarters of its deposits in cash and promised to pay the last quarter in freshly printed shares of itself.

That works while the shares hold their value. It fails the moment they do not.

Why anyone held TITAN

TITAN rose because Iron Finance paid people to hold it. Users could lock up pairs of tokens in pools that traders used to swap one for another, a practice crypto calls yield farming, and earn fees plus rewards paid in TITAN. The advertised annual returns ran into the hundreds and, on some pools, thousands of percent. Each new depositor needed TITAN to join, and each reward was paid in more TITAN, so the price kept climbing. Cuban's pool on QuickSwap, a Polygon trading venue, paired TITAN with DAI, another dollar token.

The returns were real only as long as TITAN's price held. They were paid in the very thing whose price depended on new money arriving.

The run

On the morning of 16 June, around 10am UTC, large holders began pulling out and selling TITAN. Its price fell from about $65 to $30 in two hours, then recovered to $52. In the afternoon the selling started again and did not stop.

The spiral ran in plain steps. TITAN fell, so IRON, partly backed by TITAN, slipped below a dollar. Holders rushed to cash IRON in. Each redemption printed new TITAN, which the redeemers sold at once. More TITAN for sale pushed the price lower, which made IRON look weaker, which brought more redemptions. Making it worse, the system priced TITAN using an average of the previous ten minutes, so in a crash it kept handing out TITAN at yesterday's prices while the market was already lower.

By the end of the day TITAN was trading near zero. Then the code broke: with TITAN's price close to nothing, the contract that handled redemptions started rejecting them, and IRON holders could not cash out at all until the team pushed a fix the next day. When redemptions reopened, each IRON returned roughly 75 cents of USDC. The TITAN part was worthless.

Who paid

The losers were the yield farmers, thousands of ordinary users on Polygon who had parked savings in Iron Finance's pools. Nobody has published a reliable count of them or of their combined losses; the $2 billion fall in deposits includes paper gains that vanished as well as money put in. Iron Finance said it was not a rug pull, blamed whales for panic selling and later offered users a compensation plan after criticism from its own community. Critics argued it was badly undercollateralised from the start and that the developers had copied a design they did not fully understand.

Cuban said he had pulled out some money before the worst of it and that "It was on me for not doing my homework." He never said how much he lost. A few days later he called for "regulation to define what a stablecoin is and what collateralization is acceptable."

The lesson nobody learned

Iron Finance did not disappear at once. Its anonymous team kept running small lending and trading products on Polygon, Avalanche and Fantom into late 2021, never holding more than a few million dollars. Nobody was ever identified or charged. In October 2026 TITAN still traded at about $0.0000000017.

In May 2022 the same mechanism ran at twenty times the size. Terra's UST was a stablecoin backed by nothing but its sister token LUNA, created and destroyed against it in the same way. When holders ran, LUNA was printed into worthlessness and about $40 billion of value disappeared. Terra's founder, Do Kwon, pleaded guilty to fraud charges in New York in 2025 and was sentenced to 15 years in prison. The warning had been published a year earlier, on Polygon, with Mark Cuban's name attached.