Carl Icahn says he is sensing opportunity in the stock market and wants to increase his stake in a top portfolio company. Icahn Enterprises plans to propose boosting its stake by more than 20% in CVR Energy a small refiner in which the activist investor is the controlling shareholder, according to drafts of statements that Icahn and his firm plan to release Friday that were viewed by The Wall Street Journal. Icahn Enterprises, known by its ticker symbol IEP, already owns about 66% of CVR’s shares outstanding.