I spent the past week in Europe, first in Sequoia’s London office and then flying to Helsinki to attend the Slush conference. For many years, various founders and investors told me I needed to “experience” Slush, but I resisted since it was a trek from the Bay Area. Two things changed my mind.

Luciana told me she does not go to many non-Sequoia events, but she attends Slush annually. Miki Kuusi founded the Slush conference before he founded Wolt. The conference has grown over the years but remains entirely organized by students. Today, it has approximately 50 full-time employees and almost 2,000 volunteers during the conference, supporting the 15,000 attendees of founders, investors, media, and even limited partners.

More importantly, the Slush organizers had the idea of having me interview Tony Xu of DoorDash and Miki Kuusi of Wolt about their partnership. I couldn’t pass that up.

Two years ago, Tony and Miki had been on the stage of Slush, right after their merger had just been announced, but they couldn’t speak in depth about it. This time, the communications teams of DoorDash, Wolt, and Sequoia wanted to leave a lasting impression on the audience, and the three teams collaboratively developed a tight arc of questions for me to ask Tony and Miki.

I threw out the provided notecards and asked different questions to extract unscripted answers. Miki retold the story that Wolt was about to raise $1.1b to finance its growth when he and the Wolt team spent time with Tony and DoorDash, reconsidered their fundraise, and decided to join forces with DoorDash because they had conviction they could accomplish more together. Tony had a similar conviction and diluted 10% of DoorDash for Wolt. Since the partnership, Wolt has effectively retained every employee, and its business has tripled.

The partnership’s success is unsurprising when you listen to Tony and Miki speak. Although founded on two different continents, DoorDash and Wolt have similar values and principles. Tony and Miki prefer to answer questions by pulling up dashboards and going to the lowest level of detail. Despite their success, both continue to focus on the future, expand their scale of ambition, and speak with humility. During the interview, we understood that Tony and Miki have immense respect for each other and can complete each other’s sentences. With DoorDash and Wolt, there is a cultural fit, an operating fit, and a strategic fit. Also, the merger was management accretive, as Miki has been granted charge of DoorDash’s international business.

All mergers had to be blessed by management teams, often their boards, and sometimes high-priced investment bankers. Usually, there is a fair amount of debate about the pros and cons and modeling the value of any merger. Yet, most mergers fail to deliver shareholder value. Hence, the discussion must have missed some key ingredients, and those financial models must have been wrong.

While that might be a fair conclusion, the models are wrong because we were wrong about the ultimate inputs, which are not the assumptions in the financial models but the people. The people are the ones who will deliver the value modeled. Mergers only work when people come together and work together. It’s been a real privilege to witness how Tony, Miki, and their teams work together.