UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

On May 7, 2019, NSA OP, LP (the "Operating Partnership") issued 13,803 Class A common units of limited partner interest in the Operating Partnership ("OP units") and 24,993 Class B common units of limited partner interest in the Operating Partnership ("subordinated performance units"), Series MI, to an affiliate of Move It Self Storage ("Move It"), one of the existing participating regional operators ("PROs") of National Storage Affiliates Trust (the "Company"), as partial consideration for the acquisition of one self storage property from Move It.

On June 21, 2019, the Operating Partnership issued 145,814 OP units and 167,774 subordinated performance units, Series SO, to affiliates of one of the Company's existing PROs, Southern Self Storage ("Southern"), as partial consideration for the acquisition of three self storage properties from Southern.

On June 24, 2019, the Operating Partnership issued 68,049 6.000% Series A-1 cumulative redeemable preferred units of limited partnership interest in the Operating Partnership ("Series A-1 Preferred Units") as partial consideration for the acquisition of one self storage property from an unrelated third party.

Following a specified lock-up period after the respective dates of issuance set forth above, the OP units and Series A-1 Preferred Units issued by the Operating Partnership may be redeemed from time to time by holders for a cash amount per OP unit or Series A-1 Preferred Unit, respectively, equal to the market value of an equivalent number of common shares of beneficial interest of the Company ("Common Shares") or 6.000% Series A cumulative redeemable preferred shares of beneficial interest of the Company ("Series A Preferred Shares"), respectively. The Company has the right, but not the obligation, to assume and satisfy the redemption obligation of the Operating Partnership described above by issuing one Common Share in exchange for each OP unit tendered for redemption and one Series A Preferred Share in exchange for each Series A-1 Preferred Unit tendered for redemption. The Company has elected to report early the private placement of its Common Shares and Series A Preferred Shares that may occur if the Company elects to assume the redemption obligation of the Operating Partnership as described above in the event that OP units or Series A-1 Preferred Units are in the future tendered for redemption.

As of June 27, 2019, other than those OP units held by the Company, after reflecting the transactions described herein, 33,096,037 OP units of the Operating Partnership were issued and outstanding (including 756,267 outstanding LTIP units and 1,848,261 outstanding OP units ("DownREIT OP units") in certain consolidated subsidiaries of the Operating Partnership, which are convertible into, or exchangeable for, OP units on a one-for-basis, subject to certain conditions).