One is that banks are reducing deposit rates because they do not need the money.
"And when deposit rates fall, they'll tend to keep out of other investments."
Low deposit rates also encourage Chinese consumers to spend more, a government goal, rather than save.
Analysts and traders said that two diverse factors were driving up the deposit rates.
The auction is often regarded as the harbinger of how banks will set their deposit rates in the weeks ahead.
In contrast, China's benchmark one year deposit rate is 3%.
The auction is widely regarded as a signal of changes in deposit rates by banks.
Late today, they reduced the deposit rate by one-quarter of a point, to 5 percent.
The spread of interest rates is the lending rate minus the deposit rate.
But more deposit rates were beginning to decline than a week earlier.