A pair of deals involving Chinese Internet titan Alibaba Group Holding Ltd. have kept Am Law 100 lawyers busy amid a frenetic final month in a record-setting year for M&A.

On Tuesday, Alibaba Pictures Group Ltd. and Willow Investment Ltd.—an affiliate of Alibaba’s Chinese rival Tencent Holdings Ltd.—announced that they had joined a group bidding to take private film distributor Bona Film Group Ltd. The deal for Bona, which has been involved in movies such as “The Martian” and “X-Men: Apocalypse,” values the target at $1 billion.