NEW YORK (Bloomberg) — Bermuda-based Tyco International Ltd., which is splitting into three companies at the end of this month, will post a $500 million pretax expense in the second quarter for the impairment of assets in its power-systems unit.The segment's assets were reviewed following Tyco's decision last week to break up, the company said yesterday in a regulatory filing.

The costs will probably be about $370 million after tax. The power-systems unit, part of the division that will become the new company Tyco Electronics Ltd., will be reported as a discontinued operation. Electronics, the world's biggest maker of electric connectors, is being spun off to shareholders along with the health-care company Covidien Ltd.

Tyco Electronics chief executive officer Thomas Lynch said earlier this year he's evaluating divisions to see what may be jettisoned to make his new company more profitable. Divesting the power-systems unit is a result of that evaluation, Tyco said. The segment is a combination of acquisitions from Lucent Technologies Inc. and Siemens AG made in the late 1990s.

Stockholders as of June 18 will get one share of Tyco Electronics and one share of Covidien on June 29 for every four shares of the parent owned, Tyco said in a statement June 8.

Shares of Tyco, which is run from West Windsor, New Jersey, rose 86 cents to $34.26 at 4 p.m. in New York Stock Exchange composite trading. They have climbed 13 percent so far this year.