It's shocking, but true.
Total household net worth as reported by the Federal Reserve in its Z.1 Releases of the Flow of Funds Accounts shows that Jimmy Carter wins the award, hands down, for the increase in this metric during the course of his presidential term as compared with all other presidents in the post-war period.
In point of fact, the zenith of growth in total household net worth clusters around ole Jimmy with Nixon/Ford just preceding him taking 3rd position and Ronald Reagan coming after him taking 2nd. The whole period from 1969 through 1988 represents the time when Americans made their biggest gains in overall wealth.
I measured the overall gain from January 1 of the year of inauguration to the January 1 of the year leaving office, as summarized here by the St. Louis Federal Reserve. The overall percentage gain is then divided by the number of years in office, either 4 or 8, to get an annualized score, which is not the same thing, obviously, as actual annualized performance. Data from Truman is only for three years from 10-1-1949 to 1-1-53. For Obama, who just barely beats Bush The Younger for dead last, the data is for 1-1-09 to 6-30-12 taken from the very latest Z.1 Release yesterday (here).
Carter +16.02 percent per year
Reagan 11.80
Nixon/Ford 10.21
Clinton 9.74
JFK/LBJ 8.78
Truman 8.49
IKE 7.39
Bush The Elder 6.17
Obama 4.92
Bush The Younger 3.43