Fantom's First Casualty: How a Tax-Dodging Tool Broke Tomb Finance's Peg

Tomb Finance, an algorithmic stablecoin project on the Fantom chain, became the network's first notable DeFi casualty — though whether the term "hack" even applies is up for debate. Rather than a conventional exploit, the incident centered on an anonymous actor who built a public tool letting users bypass the protocol's sell tax, and on the Tomb team's subsequent decision to shut down that same tax mechanism.

01A tax nobody wanted to pay

Tomb Finance's own site describes TOMB as "a taxed token, which means you will pay a service fee when selling TOMB." That fee was enforced by a mechanism called the Gatekeeper, designed to hold TOMB's price to a peg with FTM. The Gatekeeper fee scaled with how close TOMB traded to that peg, rising as high as 20% as the token approached parity with FTM. Fees collected this way funded the DAO, which either sold half for FTM while adding the other half as liquidity above peg, or burned the collected TOMB when the price sat below peg.

A tax that steep proved unpopular. An unidentified user found a way around the Gatekeeper and packaged it as a public interface at notomb.tax, advertising a smaller fee than the standard gatekeeper tax. An example transaction from the tool is on record at 0x0a967da..., routed through a dedicated tax-dodging contract at 0xC1C6caCb78466a555b11dA0Df6D0BB07a1Afb708.

02The team's response made things worse

Confronted with a publicly advertised way to skip the tax, the Tomb team opted to disable the Gatekeeper outright — which also removed the DAO's mechanism for defending the peg. Once this became known, TOMB lost its peg, the token price fell sharply, and social media reaction turned hostile. The Tomb team stated that this was not a hack.

The episode raises an awkward question the project itself posed in its own FAQ: what's the point of a token pegged to FTM's price if you could just hold FTM directly? Charging a 20% fee for using the token as designed sits uneasily next to Tomb's stated goal of offering, in the project's words, "a mirrored, liquid asset that can be moved around and traded without restrictions."

03What insiders reportedly said

A reader who was present in a Tomb Discord voice call relayed details to the outlet's Telegram group. According to that account, the team appeared to have known about the tax workaround for weeks before the public tool surfaced, at which point the developers disabled the Gatekeeper tax. The reasoning offered internally was reportedly that since no one was directly losing funds, it didn't constitute a rug pull or exploit.

The same account also claimed the call revealed that Tomb had already been spending DAO treasury funds — described as "100s of 1000s" — to prop up TOMB's price and defend the peg prior to this incident, suggesting the Gatekeeper tax alone had not been sufficient to maintain stability even before the workaround appeared.

04Takeaway

The incident is presented as another example of an algorithmic stablecoin design falling short: a defensive fee mechanism was undermined by a publicly available workaround, the team's response of disabling that mechanism removed the peg's main support, and internal DAO spending to defend the price reportedly predated the public controversy.