Brookdale Senior Living leaped ahead of Emeritus Senior Living to become the largest senior living operator in 2012, according to the Assisted Living Federation of America.

Brookdale’s acquisition of the operations of Horizon Bay Retirement Communities pushed it to the top of ALFA’s annual Top 80 Largest Providers List for 2012. The list ranks for-profit senior living operators by total resident capacity — as of Jan. 1, 2012 — as reported by each company. The acquisition gave Brookdale a total of 63,472 residents.

Besides the flip-flopping of Emeritus and Brookdale, the rest of the top five operators stayed the same, with Holiday Retirement at No. 3, Sunrise Senior Living at No. 4 and Life Care Services in the No.5-spot. When breaking out just assisted living beds, Emeritus remains the country’s largest operator.

According to ALFA, real estate investment trust-based acquisitions, higher absorption, big management deals and small construction rates contributed to the number of shakeups in ALFA’s top-80 list. Those 80 providers account for a total operational resident capacity of nearly 504,000 — for a 9% jump in 2011, according to ALFA.