Weber Shandwick, Edelman and MHP are involved in the second round of pitching, with the result expected to be announced in the autumn.
The closed pitch follows a review of the market by Sky, which is looking for an agency to help define its corporate narrative. It comes as Comcast and Twenty-First Century Fox make rival bids for the listed broadcaster.
Finsbury will continue to handle financial comms around the bids. The financial PR brief is expected to come to an end following the bidding process, and be replaced by the broader corporate comms account.
PRWeek understands that Finsbury, which has worked with Sky for 15 years, declined to pitch for the new corporate brief.
The pitch is being overseen by Debbie Klein, who joined Sky as group chief marketing and corporate affairs officer from Engine earlier this year, along with Gavin Davis, director of corporate communications and campaigns.
A Sky spokeswoman said: "Sky’s business and the agency landscape have evolved considerably since our last review, so as good practice we are reviewing our corporate agency support."
Other Sky agencies are not affected by the brief. These include Fever, which works on NOW TV and Sky Q; Premier PR, which handles publicity; and 33 Seconds, which has a social media brief.