As the bull market reaches its eighth year, foreign investors are shifting their focus from trophy assets to safer bets like student housing.

The student housing sector has been deemed "recession-proof" for its ability to weather the storm that a financial crisis can bring. While enrollment in colleges has been on the decline since 2010, enrollment in public universities has increased — particularly in the case of Tier 1 postsecondary schools with STEM programs. Residences near these universities have also become sought-after assets, the Wall Street Journal reports.

Nearly half of the student housing transactions this year have been driven by foreign capital. This is up 6% from 36% in 2017 and 21% in 2016, according to the WSJ.

Last year, Scion Group, the Canada Pension Plan Investment Board and Singapore sovereign wealth fund GIC formed a joint venture to purchase three U.S. student housing portfolios for $1.6B. In January, the JV announced a $1B acquisition of another 22 student housing properties. Since its inception in 2016, the JV has purchased a total of $4B in student housing assets in 52 university markets.

Similarly, Mapletree Investments Pte, which is owned by Singapore-based Temasek Holdings, acquired an 850-bed student housing facility in University City, Philadelphia, for $197.5M.