Last month, Mary Kay said it might be forced to sell part of its Avon stock because of I.R.S. problems.
Even analysts who have "buy" recommendations on Avon stock are not betting on growth.
Avon Products made a change that would thwart Chartwell from voting a huge block of Avon stock at the annual meeting.
Responding to the news, Avon stock jumped $5.50 a share, to $36.75, raising the market value of Avon's 53.9 million shares to nearly $2 billion.
Since it began acquiring Avon stock in 1989, Chartwell fought with management over the price of the company's stock and how to raise it.
On the New York Stock Exchange, Avon stock rose $1, to $36.50 a share.
"Her real test will be the second quarter forward," said Diana K. Temple, an analyst at Salomon Brothers who says she likes Avon stock.
A group that includes Robert Bass, the Texas financier, also owns 3.4 million shares of Avon common stock, Mr. Cox said.
There are 56.6 million shares of Avon stock outstanding.
The change is meant to discourage Chartwell from buying more Avon stock.