Shareholders of Lamar Advertising Co., the Baton Rouge-based outdoor advertising giant, have approved its conversion to a Real Estate Investment Trust.

The trusts don’t pay corporate income taxes as long as they distribute 90 percent of profits to shareholders.

In order to complete the conversion, Lamar formed a merger with a wholly owned subsidiary, Lamar Advertising REIT Co. The merger became effective at one minute before midnight

Lamar is one of the largest outdoor advertising companies in the world, with more than 144,000 billboards, 2,000 digital displays, and 34,000 transit signs.