It's a macro identity: the difference between income and consumption, less investment. It's also the sum of the government deficit and net exports.
According to the most recent NIPA tables, in the 3rd quarter consumption increased by 1% (annualized) while investment decreased by 10.5% (annualized). Accounting for their relative weights in GDP, this means that the private sector deficit increased by about .2% in that quarter.
Christian