Arena’s $200 million Series B lifts its valuation from $1.7 billion to $3.1 billion

Arena, the AI model leaderboard formerly called LMArena, said on Oct. 8, 2026 that it had raised a $200 million Series B at a $3.1 billion valuation.

The company’s previous round was a $150 million Series A in January 2026, at a $1.7 billion post-money valuation, according to TechCrunch. The new figure is about 1.8 times that amount. TechCrunch describes the change as a near doubling in roughly ten months.

The January round that set the $1.7 billion base

Reuters reported on Jan. 6, 2026 that the company raised $150 million, with Felicis and UC Investments as co-leads. Andreessen Horowitz, The House Fund, Kleiner Perkins and Lightspeed Venture Partners also took part. Reuters said the valuation had tripled from the prior figure within roughly eight months. It did not say whether the $1.7 billion was pre-money or post-money.

Reuters identified Anastasios Angelopoulos as co-founder and CEO. He said that measuring the “real utility of AI” requires putting models in the hands of real users. An earlier $100 million seed round, led by Andreessen Horowitz and UC Investments, had been raised in May, according to the same report.

Revenue on the record
TechCrunch reports that Arena had $30 million in annualized revenue at its January round and reached $100 million in annualized run-rate revenue in June.

Revenue figures and the new investor list

TechCrunch reports that Arena had $30 million in annualized revenue at the time of the January round. It reports that the company reached $100 million in annualized run-rate revenue in June. The company’s own post says it has passed $100 million in annualized revenue but does not give a date.

A related summary linked from the company’s post, dated June 29, 2026, reports the same $100 million milestone. On TechCrunch’s figures, run-rate revenue rose a little more than threefold between January and June. Reuters gave no revenue figure for the January round, so the $30 million number rests on TechCrunch alone.

TechCrunch names Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Endeavor Catalyst, a16z and Felicis among the participants, plus others. The company’s post also names Acrew Capital, which TechCrunch does not mention, and lists existing investors including AMP PBC, QuantumLight and The House Fund. Neither January lead, Felicis nor UC Investments, is named as a co-lead in October. Felicis appears as a participant.

An Alignment Index and a safety benchmark come next

The company released a preview of its Alignment Index alongside the round. It starts with three signals checked against real agent traces: unauthorized action, false attribution and deceptive completion. The post says these signals draw on definitions from OpenAI and Anthropic system cards. It shares methodology and initial results for more than 20 frontier models.

The company says it will add signals to the index one at a time and keep updating the leaderboard as it expands them. It also says it plans to build an independent, community-driven benchmark for AI safety and alignment. The post gives no dates for these steps, so the timing remains open as of Oct. 9, 2026, when the post was last updated.

First, the revenue figures come from different sources and dates.

What founders can take from the round

The sources do not say what Series B investors look for. The points below therefore stay with the figures that were reported.

First, the revenue figures come from different sources and dates. TechCrunch gives $30 million for January and $100 million for June, while the company’s post gives its $100 million milestone without a date.

Second, the round was announced alongside a product release, not only a valuation. The company released its Alignment Index in parallel with the round and says it plans to expand the index one signal at a time, without giving dates.

Third, the lead investors changed between rounds. The company’s post lists Felicis among its existing investors.

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