The Globe and Mail reports in its Thursday edition that ConocoPhillips on Wednesday agreed to buy Marathon Oil for $22.5-billion (all figures U.S.). A Reuters dispatch to The Globe reports that the U.S. oil and gas industry has been riding a consolidation wave over the past two years as companies look to bolster reserves and create economies of scale. Last year was one of the most active, with about $250-billion in deals struck. The momentum has carried over into this year as the stock market continues to boom and as U.S. shale oil production scales new records. ConocoPhillips, last quarter, was the third-largest oil and gas producer by volume in the Permian basin, the top U.S. shale oil field. The deal follows Exxon Mobil's $60-billion acquisition of Pioneer Natural Resources that was announced in October, and Chevron's proposed $53-billion merger with Hess that was approved by the latter's shareholders on Tuesday. The consolidation activity in the industry has attracted increased antitrust scrutiny. The Federal Trade Commission, however, recognizes that oil is a global market and the deal represents a "very, very small percentage of that global market," says ConocoPhillips chief executive officer Ryan Lance.