13-week high after it said it would sell its US unit, ISS Inc., to Aaxis Ltd., a Canadian company owned mainly by Michael A. Ashcroft, chief executive of ADT Ltd.

Shares in the world's largest cleaning company rose to as high as 143 kroner, up 12 kroner from yesterday. They traded recently at 140 kroner.

ISS also said that before the sale is completed, it will buy a 25 percent stake in Aaxis for about $3.6 million.

The sale of ISS Inc. includes ISS' operations in Mexico. Aaxis will also begin talks with the company about acquiring ISS' Brazilian unit. If the sales proceed, ISS will have removed itself from full ownership of its operations in North and South America and will be focused on Scandinavia and Europe.

ISS Inc. is estimated to be worth about 550 million kroner ($96 million) to a buyer willing to assume the company's debt, which was 1.05 billion kroner at the end of 1995, analysts said.

By keeping a minority stake in the Americas, the company can retain the prestige of having Aaxis using its logo and name.

Aaxis, which has no operations and had total assets of $10.9 million in cash as of the end of 1995, will be listed on the Montreal Stock Exchange, ISS said. Aaxis is to develop building and janitorial services in North America.

ISS Inc.'s chief executive Martin O'Halloran will continue to head the company under the new owner. Ed Turner, deputy chairman of ISS Inc.'s board, will also remain in the company.

News of the sale came just two weeks after ISS said it might sell its US unit.

On August 15, ISS said it was considering selling 75 percent of its US unit after reporting a first-half net loss of 2.03 billion kroner ($355 million).

At that time, ISS said it was negotiating with about five interested parties concerning the sale of ISS Inc.

ISS said it chose to sell to Aaxis because it could keep a stake in the US and see its operations continue under the name ISS.

"We feel very secure about this deal because there's a serious buyer who has the necessary funding to make the transaction,'' said Joern Wendel Andersen, chief financial officer, in an interview. "He's a person who knows the branch well. ISS has done business with Michael Ashcroft in the past.'' In December, 1988, ISS bought ADT Oxford in England, and in early 1989 it bought Mediclean in the US from Ashcroft.

In 1988, ISS bought ADT's North American cleaning activities, the North American Building Maintenance Division, for $69 million.

Bermuda-based ADT, the largest security company in North America and the UK is not involved in the purchase, the company said. ADT is currently the object of a $4 billion takeover by Republic Industries Inc.

"ADT is in no way related to this transaction,'' Wendel Andersen said.

The company said earlier it had taken a $146 million charge to cover errors due to "fictitious accounting'' in the US and associated costs.

"The sale of ISS Inc. will not require further write-down, if completed on the terms outlined in the letter of intent,'' ISS said in a statement.

The news of the sale and the fact that no more charges will be taken were welcomed by analysts.

"It's a good signal,'' said Steen Clausen, analyst at Nykredit Bank. "To properly evaluate it though, we will have to see some numbers.'' ISS said both parties had agreed not to disclose the price.