Not sure if this an universal offer, thought I will post anyways.
If you manage to reach five successful referral, Stake will give you another free Dropbox stock on top of the usual free stock for every successful referral.
Bonus Dropbox Stock after 5 Successful Referrals on Stake
10
Referral Links
Referral: random (28)
Referrer and referee get free stock.
Related Stores
I think it's targeted. My emails say I can get stake black for 6 months instead (approx $27 worth)