Aeon Co. announced a package of defensive measures Wednesday that it will take if a hostile bidder tries to acquire at 20 percent or more of the voting rights in the retailer.

Declared bidders will be required to wait up to 90 days before purchasing shares. If a prospective bidder fails to comply, Aeon will take all possible defense measures, such allocating equity warrants to existing shareholders, Aeon said.

The retailer will determine whether a takeover bid is friendly or not by requiring the bidder to submit information, including the purpose of the bid, in advance.

Aeon will require the bidder not to purchase shares for 90 days if the acquisition involves share swaps and other noncash means, currencies other than, yen or if the bidder intends to make major changes to the structure or operations of Aeon and its group companies.

In other cases, the bidder will have to delay the purchase of shares for 60 days to give the board of directors time to analyze information it provides.

An increasing number of firms are adopting defenses to discourage hostile takeovers before a new law designed to facilitate mergers and acquisitions takes effect May 1.