United had swept into a 3-1 lead after goals from Wayne Rooney, Danny Welbeck and Nani cancelled out Nikica Jelavic’s early headed opener.
David Moyes’ men responded through Marouane Fellaini before Rooney made it 4-2 with his second strike of the afternoon.
But the visitors mounted a remarkable comeback and scored twice in three minutes, with Jelavic making it 4-3 before Steven Pienaar netted the dramatic equaliser.
The draw means Manchester City can close the gap to their local rivals to just three points with victory at Wolves ahead of the all-important Manchester derby at Etihad Stadium on 30 April.
“We’ve thrown it [the match] away, no question about that,” Ferguson told the BBC after the game. “It’s hard to imagine it happened, how poor we defended.
“It was a bad performance by us, they were soft goals, yet some of our football was magnificent and our forward play didn’t deserve that. Their goals were very soft, easy, no challenges on their goals. That’s unusual for a team going for a championship; you should see the game out.
“We had a chance to make it 5-2, hit the post and they went up the other end and gave themselves hope. There was a lot of rain on the pitch – it slowed our possession down.
“We’ve got to get a result at Etihad Stadium now, it’s a derby of amazing proportion – probably the most important derby game in my time. We have to go there, perform in right way and not give away goals.”
Everton boss Moyes was understandably delighted with his side’s battling display at Old Trafford.
“The effort they put in was absolutely brilliant,” he said. “We came to win the game, we felt we had been a bit hard done by lately.
“Today was a chance to play in another big game and stop people thinking our season was over. I don’t think at any time we deserved to be two goals down.”
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