(Reuters) - The all-stock merger of CBS Corp and Viacom Inc is expected to close on Dec. 4, the companies said on Monday.Shares of the combined company, which would be renamed as ViacomCBS Inc, are expected to start trading on Nasdaq from Dec.5 under the new ticker symbols "VIACA" and "VIAC", the companies said.Earlier in August, CBS and Viacom agreed to merge, creating a company with more than $28 billion (21.7 billion pounds) in revenue, as an increasingly competitive media landscape..