A group of shareholders in auto parts giant Magna International who oppose its deal to buy control from founder Frank Stronach said Wednesday they plan to appeal a ruling that gave the transaction the go-ahead.

The plan would give founder Stronach's family trust more than $1 billion in cash and shares.

Some shareholders oppose the deal because of the size of the premium founder Frank Stronach and executive vice-chair Belinda Stronach, his daughter, would receive. (Frank Gunn/Canadian Press)

The Canada Pension Plan Investment Board, Ontario Teachers' Pension Plan, OMERS and British Columbia Investment Management Corp. confirmed Wednesday that they will join the appeal.

The four pension fund managers are part of a larger group of minority shareholders opposed to the arrangement because of the size of the premium it will give the Stronachs.

"BCIMC remains of the view that the arrangement is unfair and unreasonable, and disproportionately favours the Stronach Trust at the expense of the class A shareholders," said Gwen-Ann Chittenden, spokeswoman for British Columbia Investment Management Corp.

Magna, based in Aurora, Ont., said it plans to "vigorously defend" the transaction.

It said it will seek to expedite the appeal, since both Magna and Stronach have the right to walk away from the deal if it isn't finalized by the end of August.

The tight deadline leaves less than two weeks for the court to rule on the shareholders' appeal.

With files from The Canadian Press