Screen Shot 2013-03-06 at 2.50.06 PMYammer founder David Sacks just decided on stage to form a Launch microfund to support five of the startups presenting at Launch.

Screen Shot 2013-03-06 at 2.48.08 PMDuring his fireside chat, Sacks pledged to invest in $250,000 in five startups of Launch organizer Jason Calacanis’ choosing. Yammer presented at Launch a few years back and has since become the events’ biggest success stories.

Yammer sold to Microsoft for $1.2 billion last year, making Sacks a wealthy man and an active investor back in startups.

With what was apparently an impulsive decision, Sacks announced that he will dedicate $250,000 million to help Launch companies get off the ground, and perhaps meet with the same success as Yammer. This is more than the $1 million Calacanis said it cost to organize the event, and any returns could potentially pay for the entire conference in the future.

How and what companies will be chosen are still unknown.