Probably 3,000$ and 12,000$ respectively?

GP is asking, how much did this investment translate into.

2007 Dollars != 2018 Dollars.

Assuming that's what was meant, and not what the other comments did:

$3000 -> $3614.05 according to https://www.bls.gov/data/inflation_calculator.htm

Probably around 0.06 * 10,000,000,000

Assuming no subsequent investments, dilution, selling of shares, etc.

So 600M is the upper bound. Drew Houston owns roughly 25% of the company now, and he probably owned ~75% at when YC invested, for a dilution rate of 3. I'd say YC investment probably has dilution rate of 10, for the real amount of 60M. Not bad, but not Whatsapp scale either.

I know. Sucks to be them, right?

Helping other people realise their dreams and only making 8/9 figures in the bargain. Can't imagine why they would bother.

Dumb question: Why would YC get diluted so much more than DH? I've started to read up on venture financing and this doesn't match my mental model for any of the mechanisms I've learned about. (Like if anything I'd expect YC to have less dilution due to follow-on/pro rata investments, if they did any.)

I believe that when founders stock is fully vested, additional grants are an option to retain the founders beyond 4 years (or whatever the founders stock beating period is). 11 years as CEO likely led to additional grants. For a much bigger example, look at the additional grant Musk got this last week for Tesla.

Using that math, the initial investment of 15000 returned 4000x

Hahaha. This comment is hilarious.