Exhibit 4

JOINDER AGREEMENT

Reference is hereby made to that certain Joint Filing Agreement, dated January 10, 2018, by and among Scott L. Bok, Bok Family Partners, L.P., the Bok Family Foundation and the Scott L. Bok November 2015 Annuity Trust (the “Joint Filing Agreement”), in which the parties thereto agreed to the joint filing on behalf of each of them of statements on Schedule 13D with respect to the Common Stock, par value $0.01 per share, of Greenhill & Co., Inc., a Delaware corporation, to the extent required by applicable law.

The undersigned hereby acknowledges and agrees to be bound by the mutual covenants and agreements of the parties to the Joint Filing Agreement

This Joinder Agreement may be executed in any number of counterparts all of which together shall constitute one and the same instrument.

[Signature page follows]

IN WITNESS WHEREOF, the undersigned hereby executes this Joinder Agreement as of this 13th day of November, 2018.

Scott L. Bok November 2018 Annuity Trust
	By:	/s/ Scott L. Bok
	Name:	Scott L. Bok
	Title:	Trustee

		CONFIRMED AND AGREED TO:
Scott L. Bok
	By:	/s/ Scott L. Bok
	Name:	Scott L. Bok
Bok Family Partners, L.P.
	By:	/s/ Scott L. Bok
	Name:	Scott L. Bok
	Title:	General Partner
Bok Family Foundation
	By:	/s/ Scott L. Bok
	Name:	Scott L. Bok
	Title:	Trustee
Scott L. Bok November 2015 Annuity Trust
	By:	/s/ Scott L. Bok
	Name:	Scott L. Bok
	Title:	Trustee

[Signature Page to Joinder Agreement]