The 1,400-foot-tall One Vanderbilt now rising next to Grand Central Terminal may finally have its second large tenant.

Sources advise that McKinsey & Co. is seriously looking at a lease for 250,000 square feet through its CBRE brokers.

To date, the 1.7- million-square-foot One Vanderbilt has just a single announced office deal: its 200,000-square-foot anchor tenant, TD Bank. It has also snared a restaurant deal with Daniel Boulud. Both deals were first reported by The Post.

Representatives of the developers, SL Green Realty Corp., the National Pension Service of Korea and Hines, have previously told analysts they are “trading paper” with several firms and expect to end up with two to three tenants in the range of 100,000 to 200,000 square feet, with the remaining space going to single-floor tenants.

While taking rents at the top of the building will be higher, some deals lower down could end up ranging from the $130s to $140s per square foot, sources said.

No comment was forthcoming from the parties.