WASHINGTON, DC-As we reported yesterday, Salt Lake City-based Extra Space Storage is acquiring a portfolio of 17 self-storage properties in Virginia for approximately $200 million in cash. The portfolio consists of some 1.5 million square feet of net rentable space in approximately 14,000 units.

As of September 30, 2013, approximately 90% of the net rentable space at these properties was occupied.

The deal highlights an asset class in the commercial real estate industry that only in recent years has gotten much attention--self-storage. In particular, the REITs that focus on this area, such as Extra Space, are often top performers based on NAREIT figures, but rarely get the same acclaim as, say, multifamily.

So, for the uninitiated: the self storage industry in the US generated more than $22 billion in annual revenues for 2012, according to industry figures. Another indication of its heft: the sector pays more than $3.25 billion each year in local and state property taxes.

There are four other public corporations in this space besides Extra Space Storage: Public Storage, CubeSmart, Sovran Self Storage and U-Haul International. That said, the industry is also highly fragmented. There are some 2,500 large and mid-sized firms that own and operate more than one facility, according to the Self Storage Association, and some 30,000 one-facility owner-operators.

The REITs, though, are the main players and they often clock in with high financial performance. For the first three quarters of 2013, according to NAREIT, the self-storage sector gained 17.15% year over year.

In comparison, for the first nine months of 2013, the total return of the FTSE NAREIT All REITs Index was up 2.89%, the FTSE NAREIT All Equity REITs Index was up 3.03% and the FTSE NAREIT Mortgage REITs Index was down 2.11%. Self-storage REITs, though, didn't best the larger market--but then again, no REIT sectors have this year. For the same time period, the S&P 500 delivered an increase of 19.79%.