Wilder also made an offer on Instagram and Joshua immediately responded saying he would accept if it was £50m.
In an exclusive interview with Sky Sports, Finkel confirmed a take-it-or-leave it $50m (£35.9m) offer had been made, with a deadline of “close of play on Thursday” (Friday 12am UK time).
“We want [Joshua] to fight Deontay in his next fight and we offered him $50m,” he told Sky Sports.
“If he accepts it, it will be there. Al Haymon and I have never not delivered what we’ve offered.
“We were offered $12.5m (£8.8m) to fight him but we have offered four times that. If [Joshua] says he is not going to take $50m, it means he doesn’t really want to fight him next.”