Despite dipping week to week, CBS’ “Big Brother” and NBC’s “America’s Got Talent” were far and away the top draws on the major networks Wednesday, a night that also saw CBS rookie drama “Extant” ebb a bit as well. Meanwhile, CW’s magic series “Penn & Teller: Fool Us” held up well in its second week.

According to preliminary “live plus same-day” Nielsen estimates, CBS opened with “Big Brother” (2.1/8 in 18-49, 6.4 million viewers overall), which was down two tenths from last week’s 2.3 (which matched its summer high) but is expected to pick up one of those tenths in the nationals; it dominated its time period in 18-49 and 25-54 (2.5/8). Following a “Criminal Minds” repeat at 9 (1.0/3 in 18-49, 4.6 million viewers overall), “Extant” (1.0/4 in 18-49, 5.9 million viewers overall) was down slightly in its second week at 10 p.m. to what appears to be its low.

NBC kicked off the night with an encore “America’s Got Talent” (1.1/4 in 18-49, 6.0 million viewers overall), followed by the timeslot-dominant “Talent” results show (2.0/7 in 18-49, 10.0 million viewers overall), which was down two tenths from last week but could pick up one of those tenths in the nationals; as it currently stands, this matches the series’ season low set the previous night when it was impacted by a country music special on ABC.

Capping the night for NBC, “Taxi Brooklyn” (1.0/3 in 18-49, 5.5 million viewers overall) was in line with last week and currently is tied with “Extant” in 18-49, though it could fall behind in the nationals as it did a week ago.

NBC and CBS tied for the night’s lead in 18-49, with the Peacock edging ahead in 25-54 and also winning in total viewers.

Elsewere, at CW, “Penn & Teller: Fool Us” (0.5/2 in 18-49, 1.5 million viewers overall) matched last week’s 18-49 premiere score, putting it nearly on par with Monday’s “Whose Line Is It Anyway” as the network’s top summer series. As might be expected, it skewed older than most CW programs, netting a 3 share in men 25-54 but just a 1 share in both teens 12-17 and adults 18-34.

Fox’s “So You Think You Can Dance” (1.1/4 in 18-49, 3.7 million viewers overall) held at the 1.1 it had done the previous two weeks — tying with ABC’s comedy repeats for third place among the Big Four

ABC aired repeats of comedies “The Middle” (1.0/4 in 18-49, 4.2 million viewers overall), “The Goldbergs” (1.0/4 in 18-49, 3.7 million viewers overall), “Modern Family” (1.2/4 in 18-49, 4.0 million viewers overall) and a second “Middle” at 9:30 (1.0/3 in 18-49, 3.4 million viewers overall). A repeat of the music special “Nashville: On the Record” didn’t do much at 10 (0.4/2 in 18-49, 2.1 million viewers overall).

Preliminary 18-49 averages for the night: CBS and NBC, 1.4/5; Univision, 1.3/4; Fox, 1.1/4; ABC, 0.8/3; Telemundo, 0.6/2; CW, 0.4/1.

In total viewers: NBC, 7.2 million; CBS, 5.6 million; Fox, 3.7 million; ABC and Univision, 3.2 million; Telemundo, 1.4 million; CW, 1.0 million.