Business Date

Facebook announced its largest acquisition ever, saying it would pay at least $16 billion for WhatsApp, a text messaging application… Mr. Zuckerberg asked Mr. Koum to dinner at his home on Feb. 9, where he formally proposed a deal and invited Mr. Koum to join the Facebook board. Mr. Koum thought about it for a few days, and the two men met again on Valentine’s Day. Mr. Koum came over to Mr. Zuckerberg’s home, crashing the dinner Mr. Zuckerberg was sharing with his wife, Priscilla Chan. They negotiated over a plate of chocolate-covered strawberries intended for Ms. Chan.

The Times

ZUCKERBERG: Hello there. May I take your coat? And briefcase?

KOUM: Thank you. I’m so sorry—I didn’t bring anything.

ZUCKERBERG: Not at all. Have a seat on the couch. I mean, if you want to sit.

KOUM: How about here?

ZUCKERBERG: That’s great. Care for a drink?

KOUM: Oh, I really shouldn’t when I’m negotiating.

ZUCKERBERG: Just one. It’s an ’87 Bordeaux. You simply must try it.

KOUM: (coquettishly) Well … twist my arm.

Zuckerberg pours him a healthy glass.

KOUM: That’s enough!

Zuckerberg smiles and presses a button on his phone. Music plays. He sits next to Koum on the couch.

ZUCKERBERG: Mind if I play some music?

KOUM: No. What is this?

ZUCKERBERG: A new independent-rock-and-roll band that Spotify recommended to me, tailored to my individual media-consumer preferences and archived history. Do you like it?

Koum nods. Silence.

ZUCKERBERG: So—

KOUM: So—

ZUCKERBERG: You go—

KOUM: You go—

They both laugh. Zuckerberg holds out his hands in a “stop” gesture.

ZUCKERBERG: O.K., you go first.

KOUM: I was just going to say, I love what you’ve done with the Facebook space.

ZUCKERBERG: Oh, thank you, though I hired outside help for that. I’m afraid I don’t have much of an eye for graphic design myself.

KOUM: You’re far too modest.

Silence.

KOUM: You wanted to say something before?

ZUCKERBERG: Well, I was thinking how, you know, you’ve got your text-messaging app with four hundred and fifty million users worldwide, and I’ve got my mobile-friendly social-networking site with 1.2 billion members, and—stop me if this sounds stupid—we could sort of join forces and see what happens?

KOUM: (bats his eyelashes) Why, whatever are you proposing, Mr. Zuckerberg?

ZUCKERBERG: That I pay you four billion dollars in cash and twelve billion dollars in stock options, with three billion dollars in restricted stock options that would vest over the next four years. And that…

Zuckerberg moves closer to Koum.

ZUCKERBERG: …you join my board.

KOUM: Wow. (takes a deep breath) Wow.

ZUCKERBERG: You seem taken aback. Forgive me if I’m too forward. I’m the kind of C.E.O. who, when I know what I want in a proprietary-app property, I acquire it. No hedging, no equivocations, no checking with the expansion-advisory committee.

KOUM: It’s just a lot to think about. This is all happening so fast.

ZUCKERBERG: I know it may seem that way. But when two giant digital companies that are exploiting people’s inability to sustain attention and meaningful relationships are so right for each other in forming a virtual monopoly that quashes all competition, there’s no such thing as “fast.”

Koum closes his eyes and drinks his wine slowly.

KOUM: Yes.

ZUCKERBERG: Yes?

KOUM: (bursts out in peals of laughter) Yes! Yes, Mark Zuckerberg, you silly fool, yes, a thousand times, yes! Oh, this is liberating! Have your legal team contact my legal team. Hopefully we can finalize the partnership by Q2 2014.

They shake hands.

ZUCKERBERG: This feels crazy.

KOUM: It does—I don’t normally make cross-platform deals with someone I hardly know.

ZUCKERBERG: You know me. (sends him a friend request on Facebook) You know me.

Zuckerberg changes his relationship status on Facebook to “In a business relationship.” Koum sends a message on WhatsApp announcing the news to his co-founder, lead investors, and mother. The two men spend the rest of the evening on their phones.

Teddy Wayne is the author of the novel “The Love Song of Jonny Valentine,” now out in paperback.

Photograph by Heike Kampe/Getty.