Exhibit 99.1

AGREEMENT AS TO JOINT FILING

In accordance with Rule 13d-1(k) under the Securities and Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing on behalf of each of them of a statement on Schedule 13D, and any amendments thereto, with respect to the Shares of Beneficial Interest, par value $1.00 per share of Pennsylvania Real Estate Investment Trust, and that this agreement be included as an exhibit to such filing and any amendment thereof.

This agreement may be executed in any number of counterparts, each of which shall be deemed to be an original and all of which together shall be deemed to constitute one and the same agreement.

IN WITNESS WHEREOF, each of the undersigned hereby executes this agreement as of February 17, 2021.

/s/ John R. Saunders

John R. Saunders

G.S. BUILDING, L.P. By: G.S. Building, LLC, its general partner
	By:	/s/ John R. Saunders
	Name:	John R. Saunders
	Title:	Manager

G.S. BUILDING, LLC
By:	/s/ John R. Saunders
Name:	John R. Saunders
Title:	Manager

2771 GAREY L.P. By: JS Office LLC, its general partner
	By:	/s/ John R. Saunders
	Name:	John R. Saunders
	Title:	Manager

JS OFFICE LLC
By:	/s/ John R. Saunders
Name:	John R. Saunders
Title:	Manager

S.F. PROPERTY, L.P By: G.S. Building, LLC, its general partner
	By:	/s/ John R. Saunders
	Name:	John R. Saunders
	Title:	Manager

SAUNDERS PROPERTY, LLC
By:	/s/ John R. Saunders
Name:	John R. Saunders
Title:	Manager

JOHN R. SAUNDERS TRUST DATED 7/14/87
By:	/s/ John R. Saunders
Name:	John R. Saunders
Title:	Trustee

THE SAUNDERS FAMILY TRUST DATED 11/07/08
By:	/s/ John R. Saunders
Name:	John R. Saunders
Title:	Trustee

17422 DERIAN L.P. By: JS Commercial, LLC, its general partner
	By:	/s/ John R. Saunders
	Name:	John R. Saunders
	Title:	Manager

JS COMMERCIAL, LLC
By:	/s/ John R. Saunders
Name:	John R. Saunders
Title:	Manager