On our Boston-Radio-Interest mailing-list, contributor Joe Ross asked about the affiliation swap between WBZ-TV and WHDH-TV in the mid-1990s. Scott wrote:

WBZ went to CBS as part of a CBS/Westinghouse alliance that was announced in the spring of 1994. By the time of the affiliation swap on 1/2/95, that alliance had evolved into the all-out purchase of CBS by Westinghouse.

I then filled in some of the background:

And, of course, that was all triggered by Fox's affiliation deal with (and later purchase of) New World Communications, which sent Detroit's WJBK, Phoenix's KSAZ, and Tampa's WTVT from CBS to Fox, which left the other three networks bargaining with Scripps for affiliations in those markets. The result was a deal that kept ABC on WXYZ, moved WCPO in Cincinnati from CBS to ABC, put ABC on Scripps's former indie KNXV in Phoenix and former Fox WFTS in Tampa, and (most important for this discussion) took ABC away from Group W's WJZ-TV in Baltimore in favor of Scripps's WMAR (formerly NBC). Westinghouse was then left with two CBS affiliates (KDKA-TV and KPIX-TV) and two NBC affiliates (WBZ-TV and KYW-TV). They decided that they wanted a chainwide deal, too, and ended up affiliating all five stations with CBS. (IIRC, there was some conflict with another deal that NBC was doing—maybe with Hearst?—that ultimately put them out of the running.)

This then left CBS with a problem: they had to find a buyer for WCAU-TV so they could affiliate with KYW-TV. Eventually they did a deal—which I think was reported at the time as the first direct sale of a TV station between two of the Big Three networks—to sell WCAU and Miami's WCIX to NBC in exchange for cash, KCNC in Denver, KUTV in Salt Lake City, and WTVJ in Miami. Denver's old CBS affiliate, KMGH, took the ABC affiliation (previously on KUSA) as a result of another chainwide deal between ABC and McGraw-Hill, with NBC ending up on Gannett's KUSA. The McGraw-Hill deal also moved KERO in Bakersfield from CBS to ABC, moving CBS to Fisher's KBAK, the former ABC affiliate.

The original Fox–New World deal resulted in changes in other markets, including Atlanta (which sent CBS from New World's WAGA to Tribune's WGNX, now WGCL and owned by Meredith), St. Louis (ABC from New World's KTVI to Sinclair's KDNL, the former Fox affiliate), Milwaukee (CBS from New World's WITI to Weigel's WDJT, with Sinclair's former Fox WCGV going to UPN), the Piedmont Triad (ABC from New World's WGHP to WNRW, now WXLV and owned by Sinclair), and Kansas City (NBC from New World's WDAF to Scripps's KSHB).

Fox has since sold a number of the New World stations—including Milwaukee, Greensboro, and Kansas City—to Randy Michaels' Local TV LLC. (A small irony here is that the Greensboro and Kansas City stations had belonged to Taft Broadcasting, later known as Citicasters, where Michaels had cut his teeth in the 1970s, before being sold to New World.) Local TV merged with Tribune in 2013.

I hope that makes it all clear.

Summary

Here's a table summarizing the changes:

Market Station Owner Then Owner on
2013-12-28		 From
Net		 To
Net
Atlanta WAGA-TV 5 New World Fox CBS Fox
WATL 36 Fox Gannett (ex-Tribune) Fox The WB
(now My)
WGNX 46
(now WGCL-TV)		 Tribune Meredith Ind. CBS
Austin KTBC 7 New World Fox CBS Fox
KBVO 42
(now KEYE-TV)		 Granite Sinclair (ex-Four Points, ex-CBS) Fox CBS
Bakersfield KERO-TV 23 McGraw-Hill Scripps (ex-McGraw-Hill) CBS ABC
KBAK-TV 29 Ind. Sinclair (ex-Fisher) ABC CBS
Baltimore WMAR-TV 2 Scripps Scripps NBC ABC
WBAL-TV 11 Hearst Hearst CBS NBC
WJZ-TV 13 Westinghouse CBS ABC CBS
Birmingham WBRC 6 Citicasters Raycom (ex-Local TV, ex-Fox) ABC Fox
WVTM-TV 13 New World Media General (ex-NBC) NBC NBC
WTTO 21 Abry Sinclair (assignment pending to Deerfield Media) Fox The WB
(now CW)
WCFT-TV 33 Service Allbritton (sale pending to Sinclair) CBS ABC
WJSU-TV 40 Flagship Allbritton (sale pending to Sinclair) CBS ABC
WBMG 42
(now WIAT)		 Park LIN (ex-New Vision, ex-Media General) CBS CBS
W58CK 58
(now WBMA-LD)		 ? Allbritton (sale pending to Sinclair) ? ABC
Boston WBZ-TV 4 Westinghouse CBS NBC CBS
WHDH-TV 7 Sunbeam Sunbeam CBS NBC
Cincinnati WCPO-TV 9 Scripps Scripps CBS ABC
WKRC-TV 12 Citicasters Sinclair (ex-Newport) ABC CBS
Cleveland WEWS-TV 5 Scripps Scripps ABC ABC
WJW 8 New World Tribune (ex-Local TV, ex-Fox) CBS Fox
WOIO 19 Malrite Raycom Fox CBS
Dallas-Fort Worth KDFW 4 New World Fox CBS Fox
KTVT 11 Gaylord CBS The WB CBS
KDAF 33 Fox Tribune Fox The WB
(now CW)
Denver KCNC-TV 4 NBC CBS NBC CBS
KMGH-TV 7 McGraw-Hill Scripps (ex-McGraw-Hill) CBS ABC
KUSA 9 Gannett Gannett ABC NBC
Detroit WJBK 2 New World Fox CBS Fox
WXYZ-TV 7 Scripps Scripps ABC ABC
WGPR-TV 62
(now WWJ-TV)		 Ind. CBS Ind. CBS
Kansas City WDAF-TV 4 New World Tribune (ex-Local TV, ex-Fox) NBC Fox
KSHB-TV 41 Scripps Scripps Fox NBC
Miami WTVJ 4
(now WFOR)		 NBC CBS NBC CBS
WCIX 6
(now WTVJ)		 CBS NBC Universal CBS NBC
Milwaukee WITI 6 New World Tribune (ex-Local TV, ex-Fox) CBS Fox
WCGV-TV 24 Abry Sinclair Fox UPN
(now My)
WDJT-TV 58 Weigel Weigel Ind. CBS
New Orleans WVUE 8 (now WVUE-DT) Ind. New Orleans Saints (ex-Emmis, ex-Fox) ABC Fox
WGNO 26 Tribune Tribune The WB ABC
WNOL 38 Qwest Tribune Fox The WB
(now CW)
Philadelphia KYW-TV 3 Westinghouse CBS NBC CBS
WCAU 10 CBS NBC Universal CBS NBC
Phoenix KTVK 3 Ind. Sander Media (ex-Belo) ABC Ind.
KPHO-TV 5 Meredith Meredith Ind. CBS
KTSP-TV 10
(now KSAZ-TV)		 New World Fox CBS Fox
KNXV-TV 15 Scripps Scripps Ind. ABC
Piedmont Triad WGHP 8 Citicasters Tribune (ex-Local TV, ex-Fox) ABC Fox
WNRW 45
(now WXLV-TV)		 Abry Sinclair Fox ABC
St. Louis KTVI 2 New World Tribune (ex-Local TV, ex-Fox) ABC Fox
KDNL-TV 30 Ind. Sinclair Fox ABC
Salt Lake City KUTV 2 NBC (88%) Sinclair (ex-Four Points, ex-CBS) NBC CBS
KSL-TV 5 Bonneville Bonneville CBS NBC
Seattle KIRO-TV 7 Bonneville Cox (ex-Belo) CBS UPN, then CBS
KSTW 11 Gaylord CBS (ex-Cox) Ind. CBS, then UPN
(now CW)
Tampa WTSP 10 Citicasters Gannett ABC CBS
WTVT 13 New World Fox CBS Fox
WFTS-TV 28 Scripps Scripps Fox ABC