Mark Coombs, who owns around 39 percent of the London-listed fund manager's shares, said he would look to reduce his stake to a "more appropriate level" over the medium term by selling up to 4 percent a year into the market.
"We think this approach is appropriate and helps to address some of the longer-term issues that may arise from a CEO with a large stake," UBS analyst Michael Werner said in a client note flagging a 'neutral' rating on the stock.
Ashmore shares were down 6.3 percent at 387.4 pence at 0912 GMT, putting them among the biggest fallers on the FTSE mid-cap index.
Total assets at end-December were $76.7 billion (£59.8 billion), Ashmore said, buoyed by $2.4 billion in new funds from both institutional and retail clients.
Revenues rose 13 percent due to higher management fee income and currency gains, but pretax profit fell 6 percent on the back of mark-to-market losses from new funds it had seeded with its own money.
Coombs said the outlook for Ashmore in 2019 was positive after a "respectable operating performance" in the opening six months of its financial year.
"The emerging markets are in good health with high GDP growth, low inflation, attractive valuations and, after a slight pause in allocations at the end of 2018, there is renewed momentum in capital flows," he said.
(Reporting by Simon Jessop; Editing by Edmund Blair and Alexander Smith)
By Simon Jessop