... about 46 percent of senior citizens in the United States have less than $10,000 in financial assets when they die. Most of these people rely almost totally on Social Security payments as their only formal means of support, according to the newly published study, co-authored by James Poterba of MIT, Steven Venti of Dartmouth College, and David A. Wise of Harvard University.

That means many seniors have almost no independent ability to withstand financial shocks, such as expensive medical treatments that may not be covered by Medicare or Medicaid, or other unexpected, costly events.