Monopoly with Springfield, MA television?

I noticed this advertisement on the dasher boards tonight at the Springfield Falcons AHL hockey game in Springfield, MA. How is one group allowed to control three of the so-called Big 4 network affiliates in one market? The stations referenced are:

WSHM-LD channel 21 Springfield, MA "CBS 3" (referring to the basic cable channel number in the area)
WGGB-TV (ABC) channel 40 Springfield, MA
WGGB-TV (FOX) channel 40-2 Springfield, MA "FOX 6" (referring to the basic cable channel number in the area)

Correct me if I'm wrong, but doesn't Merideth own the "CBS 3" station? I know it's operated by WFSB-TV (CBS) channel 3 of Hartford.

[The Big 4 station not showing here is WWLP-TV (NBC) channel 22 of Springfield, MA. They're owned by LIN Broadcasting.]

It's a completely legal triopoly; WSHM-LD (CBS 3) is a low-power station, and the FCC has no limits at all on how many a broadcaster can own in a market. Fox 6 is merely a subchannel of WGGB. Meredith purchased WGGB, and in turn the Fox subchannel affiliation also last year. Meanwhile with the Meredith/Media General merger (or not depending on if Nexstar gets its way), there's no way that merger would be able to go through without WWLP or WGGB being sold off.