Canadian publisher Thomson Corp. has agreed to buy Reuters for about $17.2 billion, creating the world's leading provider of news and data for professional markets.

Reuters Founders Share Company, which has the power to block a change of ownership at the 156-year-old company, backed the deal but it still needs regulatory clearance and shareholder approval, Thomson and Reuters said in a statement on Tuesday.

Thomson said it would do what was required to win antitrust clearance. Reuters Chief Executive Tom Glocer, who will head the combined Thomson-Reuters group, declined to predict how long the process would take but said major disposals may not be needed.

"I would not expect we would need to make any divestitures," he said on a conference call with reporters.

The companies say the combination is a natural fit across geography and products, bringing together Reuters strength in real-time news and data with Thomson's historical information.

"We're creating a new force in a world of multiple information sources," Glocer said.

For Thomson, the combination of the two companies adds muscle to its financial services business. For Reuters, it reduces its dependence on financial markets and opens up opportunities in news and research for other professionals.

The Thomson family, which owns 70 percent of Thomson Corp via its Woodbridge holding company, backs the takeover.

REVENUE SPLIT

Thomson-Reuters will have revenues of more than $11 billion, 60 percent from its combined financial information and news business, to be called Reuters, and 40 percent from its law, tax and science markets, to be called Thomson-Reuters Professional.

With 34 percent of the financial information market, it will overtake privately-owned rival Bloomberg LP, which has 33 percent, according to industry newsletter Inside Market Data.

Thomson has been building its financial data business as it looks to tap into booming global markets. It sold its education unit for $7.75 billion last week and will use the proceeds to fund the cash element of the Reuters deal.

Woodbridge, which will own 53 percent of Thomson-Reuters, has pledged to support the Reuter Trust Principles of integrity, independence and freedom from bias.

Unions representing Reuters staff in Britain, Canada and the United States wrote to Reuters Founders Share Company trustees on Monday, expressing concern about the impact a single controlling shareholder could have on Reuters news values.

Trustees' chairman Pehr Gyllenhammar said the takeover would underpin Reuters global leadership in news and data.

"We are satisfied that the commitments made by Thomson-Reuters and Woodbridge will ensure the endurance and protection of the Reuter Trust Principles in a new and exciting context," he said in a statement.

Woodbridge will be granted an exemption to the 15 percent shareholding limit set by the Reuters Trust Principles as long as it remains controlled by the Thomson family.

The companies expect to make over $500 million of annual savings within three years of completion of the deal.

Bear Stearns and Perella Weinberg advised Thomson on the deal. Reuters lead advisers were UBS and Blackstone.