They didn't lose SO MUCH MONEY, that's the thing. The article link points that out. They "lost" money on paper by handing out stock/equity to attract talent. Their actual financials, while underwhelming, looked solid.

WhatsApp was a very lean shop (and, btw, mostly (all?) FreeBSD). At acquisition, IIRC, they had about 40 employees total (or maybe it was 40 engineers).

I think if I remember correctly one of their main cost was paying a service like twilio (or something like that) to verify phone numbers of users when they registered to use whatsapp. Anybody has an idea if they are still outsourcing that verification part to a third party or doing in-house at Facebook?