Joe Francis Sex Tape -- SOLD ... But Will Never Be Released

The Joe Francis sex tape has been PURCHASED by a major porn company ... but the footage will never, ever, ever, ever see the light of day, TMZ has learned.

We broke the story ... a sex tape featuring the "Girls Gone Wild" honcho and his smoking hot girlfriend was being shopped to various media outlets. Francis had threatened to sue everyone and their mother over the tape, claiming it was stolen from his GF's iPad.

But Francis can call off his legal pit bulls (for a change) ... thanks to a HUUUUGE favor from Vivid Entertainment honcho Steve Hirsch.

Turns out, the two porn moguls are friends (same porny circles) ... and when the person selling the tape went to Vivid, Steve decided to do Francis a solid and snatched it off the market (price: unknown).

Hirsch then turned around and gave all of the footage to Joe, along with the promise he'd never release the tape.

As for why the porn kings didn't involve police ... Hirsch told us, "Because of the time-sensitive nature of the situation I made a decision to expedite the process and return the movie to its original owner."