Peter Todd Takes Over MARA's Slipstream After a $115 Million Coldcard Hack

I've been staring at mempool policy documents for a decade, and I can count on one hand the number of times a hire in this corner of Bitcoin made me sit up. Thursday was one of them.

Peter Todd is now the lead maintainer of Slipstream, the private mempool that MARA runs. The MARA Foundation announced it. He'll develop it and operate it. That's a bigger deal than it sounds, and not for the reason most people will give you.

Look, mempool policy sounds like plumbing. it's plumbing. It's also where every argument about what Bitcoin is actually for gets settled, quietly, by maybe forty people and a handful of miners. So when the guy who co-authored replace-by-fee and built OpenTimestamps takes over a miner's private relay lane, you should pay attention.

What Slipstream Actually Does

Here's the mechanic. Normally when you broadcast a Bitcoin transaction, it goes out to the public peer-to-peer network. It sits in the mempool, visible to anyone running a node, waiting for a miner to scoop it up. Everyone sees it. Everyone can analyze it. That's the design and it's usually fine.

Slipstream skips that step. You submit your transaction straight to MARA Pool. It stays private until the moment it lands in a block. No public gossip, no visible mempool entry, no window for someone to watch your transaction and react to it.

Why does that matter? July's Coldcard exploit. Attackers pulled more than $115 million out of hardware wallets. Part of that surface was information leaking before confirmation. If your transaction is sitting in a public mempool and someone can tie your public key to it, you're exposed in ways a firmware audit won't catch.

Private relay doesn't fix bad firmware. But it does close a door. Which seems like an even stronger argument for taking relay rules seriously instead of treating them as a developer's hobby.

Slipstream isn't brand new. It first drew attention in 2024 when MARA used it to push large Ordinals inscriptions. Since then it's hosted research: Quantum Safe Bitcoin, and Binohash, a way to emulate covenants without a soft fork. Read that again. Covenants, the thing people have spent years fighting about at the protocol layer, being approximated at the relay layer.

Todd's résumé is the whole point here. BIP 125, replace-by-fee, is standard behavior now, and it was radioactive when it landed. He built OpenTimestamps. In 2024 he launched Libre Relay, a Bitcoin Core fork with looser rules for non-standard transactions. His stated position is simple. Mempool policy should reflect what the market will pay miners to mine, not what a small set of maintainers thinks people ought to do.

That's a philosophy, and it's a controversial one. Naturally.

The Part Nobody Wants to Say Out Loud

Private mempools concentrate power. There's no way around that sentence. If transactions can bypass the public network, then the miner running that lane sees things first, chooses what to include, and sets terms. That's a real shift in the shape of the market.

Coinbase has run something similar for years, so the precedent isn't new. But MARA is the largest publicly traded mining company around by hashrate, and it just handed its private lane to one of the most opinionated protocol developers alive. That combination is new.

Does it centralize Bitcoin? Some people will say yes and they'll be very loud about it. I think the honest answer is duller. Miners have always had discretion over what goes into their blocks. Slipstream doesn't invent that power, it productizes it and makes it visible. The real question is whether the public mempool stays the default or quietly becomes the slow lane.

Here's the business angle, which is the only one I genuinely care about. MARA has been squeezed. Post-halving block rewards are what they're, and the fee market has been thin. Slipstream gives the company a differentiated product. If you're an inscription project, a research team, or someone who needs privacy before confirmation, you now have a specific reason to route through MARA. That's revenue that doesn't come from hashrate.

And that matters for a stock that trades on the price of Bitcoin plus a multiple on its operational story. Spare me the roadmap. This is the roadmap. A private relay run by the man who wrote replace-by-fee is a moat you can point at on an earnings call.

The losers are the privacy purists who wanted this solved at the protocol level, plus the node operators watching a growing share of transactions they can't see until they're already confirmed. The winners are MARA shareholders and anyone who's been burned by pre-confirmation exposure.

I'll also flag the research angle, because it's underrated. Quantum Safe Bitcoin running through Slipstream means post-quantum signature schemes get tested in a live relay instead of a testnet nobody uses. Binohash means covenant-style behavior gets prototyped without waiting for a soft fork that may never arrive. That's how protocol ideas get stress-tested. Not in mailing list threads. In production, with real money, run by a maintainer who ships.

Is that risky? Sure. Everything interesting in this industry is risky.

What You Should Actually Do With This

If you're a regular Bitcoin user, nothing changes today. Your transactions still go through the public network and that's still fine for the overwhelming majority of transfers. Don't let anyone scare you into thinking the mempool is broken.

If you hold serious amounts and you've had a hardware wallet scare in the past year, this is a tool worth understanding. Not because Slipstream is magic, but because pre-confirmation privacy is a real gap in most people's threat models. Folks spend months obsessing over seed phrase storage and zero minutes thinking about what's visible while a transaction waits.

If you're watching MARA as an investment, watch the fee mix. If Slipstream volume shows up in reporting as a meaningful line item, that's the tell. Not the announcement. The numbers, six months out.

And if you care about Bitcoin governance, pay attention to who ends up maintaining the private lanes. Relay policy is where the real arguments happen now. The soft fork fights get the headlines. The mempool rules decide what's actually possible.

I've seen enough to know the boring infrastructure hires are usually the ones that matter. This is one of them.