Shari Redstone Todd Williamson Archive | Contributor | Getty Images

It's been almost six months since CBS hired search firm Korn Ferry to help select a new CEO for the broadcast network. Joe Ianniello has been filling this role on an interim basis since September after Les Moonves resigned amid sexual misconduct allegations. And still, no CEO has been hired. No announcement is imminent either, according to a people familiar with the matter, who asked not to be named because the search process is private. CBS has never publicly offered a timeline for how long it would take the company to name a new CEO. But sources close to the CBS board told CNBC in January that the company hoped to name one by the end of the first quarter. That soft deadline has now come and gone. So what's going on?

M&A plan

Shari Redstone, the vice chair of both CBS and Viacom, would like to put together the two companies, according to people familiar with the matter. But she can't magically will it to happen — she'll need the CBS board to come to the same conclusion. Redstone wants a larger CBS in part so it can compete for National Football League broadcast rights when they're up after the 2022 season, as CBS's retransmission fee growth is largely dependent on having NFL games. But there will probably be a slew of bidders for the rights, possibly including tech giants Apple and Amazon, who have much larger balance sheets. If CBS is to merge with Viacom (or anyone else), a CEO would obviously want to know this before taking the job. According to several sources familiar with the matter, Redstone would like current Viacom CEO Bob Bakish to run or be the No. 2 at a combined CBS and Viacom. It's important to Redstone that Bakish can work well with whomever is named CEO at CBS when the companies come together, the people said. CBS has more clarity on what a merger with Viacom will look like now that Viacom has reached a multiyear carriage deal with AT&T and its DirecTV subsidiary. The sides know each other very well and agreed on economic terms for a deal last year, so due diligence shouldn't take too long. If the board wants to start merger discussions, it doesn't make any sense to name a CEO before making a decision on M&A. The two decisions would naturally be paired, especially if the CBS CEO is to become the No. 2 to Bakish at a combined company.

CBS hasn't found the right candidate