Ennis has signed a three-year deal with the League One club for an undisclosed fee, with United securing a 50% sell-on clause, a buy-back option and a matching rights provision as part of the agreement — in keeping with the club's approach to academy departures this summer.
The 21-year-old had not featured in United's preseason and joined Stockport having enjoyed an impressive campaign on loan at Fleetwood Town last season, scoring six goals and providing eight assists in 46 appearances. Ennis originally signed for United in 2021 after turning down a scholarship contract at Liverpool, and posted a farewell message on Instagram confirming his exit.
"After a rollercoaster five years the time has come to move on from Manchester United," he wrote.
"I'll always be grateful for the memories, the people and the experiences that have shaped me both on and off the pitch. It's been an honour to wear the shirt and represent this club.
"I want to say a big thank you to all my coaches, staff and teammates for making my time here so special. It's something I'll always cherish and look back on with pride. Thank you for everything."
While Ennis's move is complete, Collyer's situation remains in progress. The 22-year-old midfielder is in talks with West Brom about returning to the Hawthorns on a permanent basis, having been part of Michael Carrick's squad throughout preseason and featuring in the second half of last week's draw with Leeds United at Croke Park while Mason Mount was unavailable through injury. It had nonetheless been anticipated all summer that Collyer would eventually leave Old Trafford, with talks over a permanent exit said to be at an early stage.
Collyer previously spent the first half of last season on loan at West Brom, making 12 appearances including three starts before returning to United in January. He then joined Hull City after recovering from a calf injury but managed only five appearances before further fitness issues disrupted that loan as well.
Hull City had been thought to be keen on bringing Collyer back to the club following their promotion to the Premier League, though a deal there has yet to materialise, leaving West Brom as the more advanced suitor for his signature.