Gagan Mac

VP Product @circle, Co-founder | Ex - Product Lead - Ray-Ban Stories @Meta, @Uber, @Twilio

[Panchu @Panchu2605]

Circle just designed @Arc to be quantum-resistant from the very first block - and most people building onchain haven't fully processed what that means.

Every wallet, every transaction, every smart contract on every EVM chain today is secured by elliptic curve cryptography. Shor's algorithm, running on a sufficiently powerful quantum computer, breaks all of it.

The threat isn't waiting for Q-Day to start. Harvest-now, decrypt-later is already live. Adversaries collect encrypted onchain data today and hold it until quantum hardware catches up. Every public key ever exposed on any chain is already in that exposure window.

NIST finalized the post-quantum standards in August 2024 - ML-KEM (FIPS 203), ML-DSA (FIPS 204), SLH-DSA (FIPS 205). The industry migration deadline is 2030. The clock is running.

What @circle built into Arc is the only answer that makes architectural sense: quantum-secure signatures live at mainnet launch, from block one. Not retrofitted. Not a future hard fork. ML-DSA, CRYSTALS-Dilithium, Falcon - built in from genesis, opt-in, no forced migration, no network reset.

The rollout covers the full stack. Wallet signatures at launch. Private VM layer next - confidential transfers shielded, public keys wrapped in symmetric encryption. Then infrastructure: TLS 1.3 with X25519MLKEM768 hybrid key exchange, HSMs upgraded. Finally validator authentication - moved only after performance testing confirms sub-second finality holds.

Wrote a full breakdown in the Arc House India chapter - why this architecture matters, what the real tradeoffs are, and why this is directly relevant to anyone building payment infrastructure in India right now.

https://t.co/91QJbhEuop

[Corey Cooper @corey__cooper]

Just had @circle agent stack due some research on what NBA analysts are saying about Game 7 of the Western Conference Finals and it's amazing how easy it is to gather intel when you can pay with @USDC via x402

[Arc @arc]

Quantum computing introduces long-term risk for digital infrastructure, from wallet signatures to validator integrity and more.

Circle’s post-quantum whitepaper explores Arc’s phased approach to resilience across:

→ USDC
→ Smart contracts
→ Validators
→ Infrastructure systems

Planning for long-term security and institutional adoption.

https://t.co/Kt8d1aPIKz

[Gagan Mac @gaganmac]

@OndoFinance Terrible news. Heartfelt condolences.

[Rachel Mayer @0xrachelita]

iOS didn't replace the phone, it gave every developer on earth the same platform to build on.

Arc does that for money.

[Jeremy Allaire - jerallaire.arc @jerallaire]

This is called @Arc

[Jeremy Allaire - jerallaire.arc @jerallaire]

We just added the ability for your agents sign-up for phone numbers and make AI-native phone calls using Circle Agent Stack and USDC. Get your agent a phone number on Twillio and make AI voice-native real-time calls with BlandAI.

https://t.co/hTGfvyqaWc

[Gagan Mac @gaganmac]

We're working more with startups more deeply than ever before. There's a lot of opportunity emerging to build high-quality financial experiences with global reach using stablecoin infra. Reach out if you think we can help at @BuildOnCircle and @arc

[Y Combinator @ycombinator]

Announcing YC Crypto deals

We're now providing crypto deals to support fintech builders funded by YC: support on tools like wallets, onramps, audits, blockchains, onchain data.

[ace @_ace_won]

The first x402 facilitator on Arc Network is live!

What that means:
→ Any API on Arc can now charge per request in USDC

→ AI agents pay automatically - no human needed

→ Humans can pay too - connect wallet, sign, done

[Jeremy Allaire - jerallaire.arc @jerallaire]

Calling @Arc Architects — I would love to back a team building this with Circle Agent Stack and Arc.

[Morpho 🦋 @Morpho]

Morpho is coming to @arc

Today: $2,500,000,000+ in USDC already earning yield on Morpho.
Soon: the open credit network will power the Economic OS built for the internet-native economy.

[Circle Developer @BuildOnCircle]

Eco integrated Circle Gateway to make multichain execution easier to scale.

Instead of pre-funding USDC on every network, Eco users can work from a unified balance and access liquidity on demand.

For builders, that means less chain-by-chain inventory management and a cleaner base for crosschain deposits, transfers, and swaps.

Learn More: https://t.co/GE205B0qP4

[Rachel Mayer @0xrachelita]

Credit is the fuel for any economy. And day 1 of Arc will have Morpho and more

[Reid Hoffman @reidhoffman]

https://t.co/QLXU6ZOTrj

[Gagan Mac @gaganmac]

It’s *the* programmable dollar.

[Peter Schroeder @peterschroederr]

99.8% of agent transaction volume on x402 is @USDC.

Data: @artemis

[Gagan Mac @gaganmac]

Read more about our plans. Android brought internet to 80% of the world's pockets. With Arc as the economic OS - we want to bring financial opportunities to every corner of the internet.

Arc token delivers the coordination mechanism that keeps us true to this mission.

https://t.co/gwNVRfAMav

[Gagan Mac @gaganmac]

We’re just getting started.

[Ali Yahya @alive_]

https://t.co/EJrDz0w0jX

[Peter Schroeder @peterschroederr]

Stablecoins are averaging nearly $10 trillion in monthly transaction volume so far in 2026 (through April), up 93% from their 2025 monthly averages.

@USDC is driving the majority of stablecoin activity, accounting for nearly 77.7% of total stablecoin volume year to date.

[JC Bahr-de Stefano @jbahrdestefano]

Wow apparently @Shopify has been quietly stacking money transmitter licenses. MTLs are state-by-state licenses that let a company legally hold customer funds + move money on their behalf

Getting MTLs means they would be able to hold and move funds themselves, instead of routing everything through @stripe

Shopify did $378 billion in GMV in '25 --> owning the rails = owning more of the economics

https://t.co/BNMnVmihO8