NBC Sports reported an 8.4 national rating and a 20 share for the race portion (5:45-6:45 p.m. EDT) of its May 6 Kentucky Derby telecast. The rating is slightly down from last year's 9.0/22 national rating for the race portion of the telecast. Since 2001, the race portion on NBC has averaged 8.7. The national rating for the entire telecast will be announced Thursday. For national ratings, one point equals approximately 1.1 million households. Earlier, the network reported a 7.4 overnight rating and 17 share for this year's coverage of the Kentucky Derby, down from 8.2/19 in 2005 and 8.3/18 in 2004. The rating measures how many households were tuned into the telecast, with each overnight ratings point equaling approximately 770,000 homes. The share measures the percentage of viewers who were tuned into the Derby telecast.This year's pre-race segment (5-5:45 p.m. EDT) generated a 5.5/13 in the overnights, down from 6.0/15 a year ago. The race segment (5:45-6:45 p.m. EDT) registered an overnight rating of 8.9/20, down from 10.0/23 in 2005. Competition included CBS' coverage of the Wachovia PGA golf tournament, and ABC' telecast of NCAA women's gymnastics. Final ratings will be reported Thursday.Top-rated individual markets for the race portion of the telecast were: Louisville (33.3/62); Ft. Myers, Fla. (15.2/29); Cincinnati (14.4/33); Orlando (14/26); St. Louis (14/29); and Buffalo (13.8/28).