Flat Capital, the investment firm managing Sebastian Siemiatkowski's wealth, has been quietly expanding its AI startup portfolio as the Klarna CEO continues to advocate for the efficiency gains enabled by the technology.
In the past year, Flat has made 13 investments in AI-related startups, including AI-powered search engine Perplexity, AI legal tool Harvey and Elon Musk’s xAi. It’s also backed Sam Altman’s OpenAI and translation company DeepL.
While CEO Hanna Andreen emphasises Flat’s “broad and flexible investment mandate”, the investment firm’s AI-led strategy comes as the firm divests away from later-stage growth companies that made up its bread and butter pre-downturn. It’s also partly peddled by Siemiatkowski’s personal interest in AI.
“For natural reasons, we came across more AI investment opportunities in the last year,” she tells Sifted.
What is Flat Capital?
In 2013, Siemiatkowski and his partner Nina quietly established an investment firm, initially called Rockwood AB, which was 100% owned by the couple.
This evolved into what is now known as Flat Capital, a “hybrid between an investment company and a family office” with a net asset value of 393m SEK (€34.42m) according to its latest filings.
“Legally, it’s an investment company controlled by Sebastian Siemiatkowski,” Andreen says.
The Siemiatkowskis remain the primary shareholders according to an interim report covering January to September 2024.
Other shareholders in Flat include AltoCumulus, the asset management and family office behind the Axel Johnson Group, Dusco AB, an entity owned by the prominent Swedish noble family the Douglas’ and H&M heiress Karolina Tham von Heidenstam.

Sourcing deal-flow
Those investors are likely attracted to in-built network that comes with having Klarna’s CEO and cofounder as chairman.
Before Andreen was appointed CEO in 2021, Flat’s deal-flow was largely sourced via the Siemiatkowskis’ strong network of VCs and founders. But as she got settled into her role, she’s established more personal relationships with some of the larger investors and founders.
“Last week, we found a company through X that we became extremely obsessed with their demos and then we managed to get a hold of them to have a meeting,” she says.
While Flat ultimately didn’t end up backing that company, Andreen estimates the investment firm met with 180 companies last year — half of which was sourced internally and the other half coming from Siemiatkowski and the board.
While Andreen admits Siemiatkowski is “very busy” and “extremely focused on Klarna”, she says he still takes an active role in the investment firm. Board meetings are scheduled in the evening so he has time to attend. If they’re closing in on a deal, they’ll communicate over WhatsApp so they can act swiftly.
“Sometimes we get an investment opportunity and we act within a couple of days,” she says. “It’s a criteria for us that we have to be swift in our decision-making.”
Sebastian Siemiatkowski's AI love affair
Sebastian Siemiatkowski has also made no secret of his belief AI should be used to speed up work. He made headlines last year after claiming AI was already capable of doing almost any job a human can, going as far as sending an AI version of himself to announce Klarna’s third quarter results to prove that point.
Flat’s setup is no different.
On the employee section of its latest report, alongside CEO Andreen and CFO Antonio Melani, the investment firm lists its 'AI-colleagues', which include DeepL as head of translations, ChatGPT as head of communications and copywriting and Harvey as head of legal. The English version of the report is also watermarked with a signpost saying it was translated by DeepL.
And the investment firm’s belief in AI is so strong that it’s willing to make small “angel” sized tickets in companies like Swedish AI talent platform Talentium and AI orchestration platform Nexos.ai, which was founded last month, just to get their foot in the door.
“That opens up the possibilities of just following them and perhaps investing more at a later stage,” says Andreen.
The AI focus marks a pivot from when Andreen first took helm of Flat. Some of the first investments she made then include a $4.9m cheque for Turkish speedy grocery app Getir, which the investment firm warned it may need to write down last year following Getir’s financial difficulties.
The listed family
Andreen admits there’s been investments that haven’t gone to plan, but says that’s in line with Flat’s risk profile.
“We’ve made investments we regret to some extent but we’ve also made investments we really believed in and didn’t go the way we wanted,” she says.
One quirk of Flat that makes it stand out from other funds set up by Europe’s founders is that it’s publicly-traded on Nasdaq’s First North stock exchange in Sweden.
Andreen, who joined only a couple months before its IPO in 2021, says it was the Siemiatkowskis' idea to take it public.
“My understanding is that Sebastian and Nina wanted to create an investor structure that could truly be long-term,” she says. “But also to give access to the kind of companies they were very privileged to be able to invest in.”
In November last year, Flat wrapped up the trading period for a 140m SEK (€12.26m) rights issue to finance its upcoming investments.
Being listed also means it has a different approach compared to a VC fund, which typically liquidate after an exit. While they welcome the returns from an M&A event or an IPO, Andreen says Flat is happy to stay on the board of companies it sees as long-term investments.
After OpenAI and delivery company InstaBee, Flat’s largest holding is in Klarna. Andreen declined to comment on what would happen to that holding post-IPO — at the tail end of 2024, the Swedish buy now, pay later player filed for an IPO in the US — but expects not much will change after the listing.
“Things can change very quickly but as of now, we’re in a strong position,” she says. “We have cash to deploy, a portfolio of companies we’re really proud of and deal-flow wise we’re in a good spot — that will continue for sure if Klarna becomes listed.”