CBS Entertainment and Warner Bros. Television have reached a deal for a two-year renewal of The Big Bang Theory, through the 2018-19 season. The pact comes on the heels of the two companies closing a deal for a spinoff prequel series, Young Sheldon, which is expected to launch next fall behind Big Bang.

The two-season pickup for CBS’ flagship series also comes after the show’s original cast members Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg and Kunal Nayyar signed new two-year contracts to continue.

I hear the renewal is being announced with no deals in place for Big Bang co-stars Melissa Rauch and Mayim Bialik, whose contracts also are up at the end of Season 10. They have been negotiating new contracts, and I hear they are close but not closed yet.

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Rauch and Bialik, both introduced as guest stars in Season 3 and becoming regulars in Season 4, had been earning about $175,000 an episode in their most recent deal. Because their characters have become an integral and equal part of the show’s ensemble, with Bialik earning four Emmy nominations for her role, the two had been seeking a major salary increase that would get their pay checks close to just under $1 million an episode Parsons, Galecki, Cuoco, Helberg and Nayyar will command after reportedly pitching in each 100,000 an episode toward Rauch and Bialik’s raises. Observers expect Rauch and Bialik to end up around or north $500,000 per episode.

While Big Bang‘s production price tag — covered in large part by CBS at this point in the series’ run — is creeping up to an eye-popping $10 million an episode, the comedy series is in its own league performance-wise. In its 10th season, The Big Bang Theory is the most-watched and highest rated scripted series on television with an average of 19.4 million viewers in Live+7 and a 5.1 Live+7 rating in 18-49. What’s more, Big Bang, the most watched comedy series since 2010-11, is still packing the elusive live audience, averaging more than 14 million live viewers for an original telecast.

Additionally, Big Bang has been used to launch numerous new CBS series, most recently Kevin Can Wait, The Great Indoors, Life in Pieces, Mom, The Odd Couple and Scorpion.

The series has generated more than $1 billion for Warner Bros TV in syndication revenue. The dearth of big network sitcoms in the past few years might help the show continue to generate strong revenue for its additional seasons on TBS and in broadcast syndication despite the fact that both the cable network and the stations have a cap on how many seasons of Big Bang they have to pick up at the original very high price, which has been met, making suture seasons potentially less valuable.

Big Bang has won four Emmy Awards for for star Jim Parsons. Chuck Lorre, Bill Prady and Steven Molaro are executive producers. The series is from Chuck Lorre Productions, Inc., in association with Warner Bros. Television. Chuck Lorre and Bill Prady are series creators.