Onex Corporation ( TSE:OCX ) is spending nearly $1 billion on a California-based tradeshow company. The Toronto-based takeout firm is acquiring Nielsen Expositions from its parent company, Nielsen Holdings (NYSE: NLSN), for $950 million. Onex ' private equity vehicle, Onex Partners III, will contribute $350 million in equity, of which Onex 's share will be $85 million. Nielsen Expositions orchestrates more than 65 business-to-business tradeshows and conferences each year.