Covid-19 has changed the real estate investment trust ( REIT ) landscape, particularly commercial property and office buildings. One REIT to consider focuses on mortgages rather than physical property: the iShares Mortgage Real Estate Capped ETF ( REM B ) , which is up 25% the last three months. “Mortgage real estate investment trusts (REITs) may sound intimidating, but their operating model is actually pretty simple,” a Motley Fool article noted. “These businesses borrow money at short-term lending rates and acquire assets that have a higher long-term yield.