The Extra Space Storage team took performance to new heights in 2021, with a record-breaking year in almost every area of the business. From innovative ways to invest capital in self storage to evolving our employee experience, our 2021 Annual Report covers some of the team’s efforts to innovate, implement, and grow. Here are some highlights of our strategy for external growth.
Through acquisitions, we increased our portfolio by 119 locations. The market for acquisitions remains competitive, and we will only pursue deals that grow our stock price. Because of our extensive network in the commercial real estate industry, we are able to acquire lease-up properties off the market, bypassing the competitive brokered market for portfolio deals. Sixty-six percent of the properties we bought were acquired via joint ventures, third-party sales, or bridge loan relationships. In addition, we often arrange these deals with joint venture partners and other structures, generating initial and stabilized yields that are higher than market averages.
An additional 265 stores were added to our ManagementPlus platform during 2021, bringing the total number of third-party managed locations to 828 by year’s end. We’re the biggest third-party manager industry-wide, and consider all our clients to be partners. These connections naturally bring the possibility of future mergers and acquisitions, bridge loans, and mutually beneficial exchanges of information and expertise. Our third-party management system not only generates revenue through management fees and tenant insurance premiums, but also increases our scalability, competitiveness, and data availability.
In its third year, Extra Space Storage’s bridge loan program has continued to rapidly expand. We originated $333 million in mortgage and mezzanine loans in 2021. This program was created so that present and potential clients of third-party management companies can get loans for properties, regardless of occupancy. This strengthens our ties to them, expands our product offerings to include management contracts, and enables us to deploy funds with a favorable return on investment. Net origination for 2021 was $156 million, and the weighted average interest rate on our mezzanine notes was 9.1%. As anticipated, we sold a sizable amount of mortgage loans to debt partners. We also bought 13 loan-collateral properties for a total of $161 million.