Mark Barnett is to leave Invesco by mutual agreement after 24 years with the business, handing over the open-ended funds he managed to James Goldstone and Ciaran Mallon, effective immediately.
The announcement comes as part of a raft of changes to its UK equity product range and investment management team led by chief investment officer Stephanie Butcher, who was appointed earlier this year.
"When I become CIO in January, I made it clear I would not shy from introducing change where I saw it necessary," said Butcher.
Of his departure, Barnett said: "I am extremely proud of my career at Invesco and for my long-term track record of value creation for my clients. I wish James and Ciaran huge success in managing the portfolios in the future."
Martin Walker, who was appointed co-head of UK equities alongside Barnett last year, will continue to lead the team, now as head of UK equities, and will manage the Perpetual Income and Growth Investment Trust.
Butcher added: "It is a credit to the quality of our team that we have the experience and capabilities of both James and Ciaran, who have worked together for seven years, to take on these new roles.
"We remain committed to our valuation-driven investment philosophy and are confident that in James and Ciaran we have the right leadership in place to capitalise on the value that exists in the UK markets and deliver long-term investment results for our clients."
Jason Hollands, managing director at Tilney Investment Management Services, said that Barnett's departure followed "a period of prolonged, significant underperformance", which has "fuelled a pattern of major outflows from the firm's once flagship UK equity funds".
"In truth, the writing on the wall for the manager has been there for some time, with Barnett moved from head of UK equities to co-head last year and the firm being dropped as manager of the Edinburgh Investment Trust in December."
Barnett's association with Neil Woodford as "former protégé" and a manager who also shared his "investments in illiquid assets" caused "extra challenges and pressures" for both Barnett and Invesco, according to Adrian Lowcock, head of personal investing at Willis Owen.
"Nonetheless, this will leave the many thousands of investors who stuck it out with Barnett with a big decision to make.
"The fact is, there are other options out there that they can take now, who have proven track records, and this could, in the short term, result in further outflows from Invesco's flagship funds."
Inheriting the funds from Woodford has lent Barnett some goodwill, but not enough, as Darius McDermott, managing director of Chelsea Financial Services, said there was "some sympathy" for the Woodford heir, adding it is "very difficult to perform well if you are constantly having to sell holdings".
Ben Yearsley, investment consultant at Fairview Investing, added that "ultimately the poor performance has been down to Barnett's investment decisions", but warned those still invested that it "feels the wrong time to bail out of these funds".
Ryan Hughes, head of active portfolios at AJ Bell, added: "While Invesco have been hoping that the steps taken to improve performance in recent months would have been sufficient, it is clear that making a clean break has been decided as the better course of action for both parties.
"With a review of the UK fund range also having taken place, Invesco clearly want to try and get their UK franchise back on the front foot. However, it will take a long time for the new managers to turn around performance."
The review of the Invesco UK Equity portfolio includes a reorganisation to "help add further clarity, differentiation and focus" and will see a clear distinction between the Invesco High Income fund and the Invesco Income fund, with the former's objective being clarified to aid investors' understanding of the income objective and benchmark.
Also included is a proposal to merge the Invesco UK Strategic Income fund with the Invesco Income fund, subject to FCA and shareholder approval.