Summer veterans ”America’s Got Talent” on NBC and ”Big Brother” on CBS tied as Wednesday’s top programs among young adults, though both lost more than a quarter of their year-ago audiences.

According to preliminary national estimates from Nielsen, the Wednesday premiere of ”Big Brother” at 8 p.m. averaged a timeslot-leading 1.9 rating/7 share in adults 18-49 and 5.6 million viewers overall, down from the 2.6 demo score for its season premiere last Thursday and 2.3 on Sunday; it was also down 27% vs. the comparable night a year ago. Later, the Eye aired repeats of ”Criminal Minds” (1.0/3 in 18-49, 5.1 million viewers overall) and ”CSI” (1.1/3 in 18-49, 5.5 million viewers overall).

At NBC, ”America’s Got Talent” averaged a 1.9/6 in 18-49 and 7.5 million viewers overall to win the 9 o’clock hour and stand as the night’s No. 1 show outright in both adults 25-54 (2.6/7) and total viewers; it was down 30% year-to-year. The Peacock net opened the night with encores of ”Off Their Rockers” (1.1/4 in 18-49, 4.7 million viewers overall) and ”Up All Night” (0.8/3 in 18-49, 2.8 million viewers overall) and closed with a repeat of ”Law and Order: SVU” (1.1/3 in 18-49, 4.4 million viewers overall).

Fox won the night with a two-hour ”So You Think You Can Dance” (1.8/6 in 18-49, 5.1 million viewers overall), which finished a smidge behind ”Talent” and ”Brother” in 18-49 and was the night’s No. 1 show in persons 12-34 (1.5/5). Unlike the other Wednesday vets, It limited its year-to-year losses to about 10%.

Univision earned a second-place finish on the night, winning at 10 p.m. in demos with ”La Que No Podia Amar” (1.7/5 in 18-49, 4.3 million viewers overall).

At ABC, 10 p.m. newcomer ”Final Witness” (1.2/4 in 18-49, 4.2 million viewers overall) appears to have edged up to a series high, providing the net with nice time-period improvement over last year’s ”Primetime Nightline: Beyond Belief.” Earlier in the evening, the net aired repeats of comedies ”The Middle” (0.8/3 in 18-49, 3.9 million viewers overall), ”Suburgatory” (0.9/3 in 18-49, 3.2 million viewers overall) and ”Modern Family,” both at 9 (1.4/4 in 18-49, 4.0 million viewers overall) and 9:30 (1.5/4 in 18-49, 4.0 million viewers overall).

Preliminary 18-49 averages for the night: Fox, 1.8/6; Univision, 1.5/5; CBS, 1.4/4; NBC, 1.3/4; ABC, 1.2/4; CW, 0.3/1.

In total viewers: CBS, 5.4 million; NBC, 5.2 million; Fox, 5.1 million; ABC, 3.9 million; Univision, 3.8 million; CW, 0.9 million.