FACTBOX-Dow breaks above 26,000 but ends below that level

Jan 16 (Reuters) - The Dow Jones Industrial Average ticked above 26,000 for the first time on Tuesday before backing down and closing slightly below that level. The Dow closed above 25,000 for the first time on Jan. 4. It took the index 23 trading days to get to 25,000 from the first time it closed above 24,000 on Nov. 30. Optimism about fourth-quarter earnings and benefits from the recently approved U.S. tax overhaul, which includes hefty corporate tax cuts, have helped to keep market momentum strong in the new year.

Here are some recent facts about the index: - The Dow is up 2.9 percent since the Jan. 4 close, and up 4.3 percent since Dec. 31.

- Boeing Co has been the index's largest percentage

gainer since the Jan. 4 close, adding more than a quarter of the last 1,000 points, with a rise of 13 percent. Second was Merck &

Co Inc , up 8.8 percent since Jan. 4. - Intel Corp has been the largest percentage

decliner since Jan. 4, down 2.9 percent, followed by Verizon

Communications Inc , down 1.8 percent.

(Reporting by Caroline Valetkevitch and Chuck Mikolajczak; Editing by Leslie Adler)