Hachette, the French media giant, offered to...

Hachette, the French media giant, offered to pay $21 a share in cash, or $415 million, to acquire Grolier, a publisher of encyclopedias and reference books based in Danbury, Conn. Hachette, Europe’s second-largest publisher, said it will launch a tender offer today, expiring April 8, for the 95% of Grolier’s 19.5 million outstanding common shares that it does not already own. Grolier’s stock rose 87.5 cents Friday to $15.875 in New York Stock Exchange trading. Hachette said acquisition of Grolier would make it the world leader in encyclopedia publishing. Grolier had no immediate comment.