Callosum Secures $100 Million Seed Funding to Scale Heterogeneous AI Infrastructure

Plural, DCVC and the UK Sovereign AI Fund piled in alongside, making the deal one of the largest seed rounds for a European AI infrastructure company to date — and a notable one, given it follows only a $10.25 million pre-seed announced back in February.

Reading the cap table

The syndicate is the story. Atomico led; DCVC brings deep-tech credibility; Plural doubled down after anchoring the pre-seed six months ago, which is either conviction or a markup it cannot refuse. Most telling: the UK Sovereign AI Fund joined the round — a signal that Whitehall is writing actual cheques into chip-agnostic infrastructure, not just publishing strategy papers. State capital under price discipline raises the bar for the next raise.

Deployment: build what Callosum calls "heterogeneous intelligence." The company is not making a GPU. It sells an orchestration layer that picks the right model and processor for each workload, then routes traffic across multiple generations of NVIDIA accelerators, AMD processors and Google TPUs based on cost, latency and energy use. The $100M cushion buys runway — burn rate against multi-cloud engineering talent will still be punishing, and runway is not victory.

The hardware angle

Alongside the financing, Callosum announced partnerships with Cerebras Systems and South Korean chipmaker Rebellions, plus a concept dubbed "programmable heterogeneity" — workloads broken into smaller computational tasks, then dispatched to suitable silicon. The thesis is clean: as the accelerator market fragments into GPUs, TPUs, custom AI chips, inference processors and photonic hardware, whoever owns the dispatch logic captures margin without owning fabs. Whether enterprises pay the premium for abstraction over vendor lock-in is the question that actually matters. Hyperscaler stacks and Nvidia's own software moat will not sit still while this layer gets built.

SECA on the side

Separately, AI-driven hardware design startup SECA is reported to have closed a seed round from LG Electronics and Bluepoint Partners, per Wowtale. No amount, no valuation disclosed. LG's cheque points to Korean conglomerate appetite for AI-native chip design tooling — a thesis that has produced more press releases than returns so far. The next data point is the one to watch.

For investors and operators flying in to sit across from these UK teams, the friction starts at the border — see the current duty-free allowance rules when entering from the EU before you pack the pitch deck in your hand luggage.