MERS, the Mortgage Electronic Registry System, is a legal fiction that—on paper—owns about half the mortgages in the United States. It was created in 1995 as a solution to the problem of slow-moving county property records offices. Banks and investors needed mortgages to move faster, so they registered once with the county in the name of MERS . . . and then basically lost track of the paperwork.
The New York Times explains why, but here’s the gist of it.