There were 65,242 suspicious activity reports (SARs) filed by credit unions last year, compared with 62,630 in 2009, according to data compiled by the Financial Crimes Enforcement Network.
SARs declined at all other types of financial institutions, FinCEN said in its new report.
There were 697,389 suspicious activity reports filed by depository institutions last year, compared with 720,239 in 2009. There were 629,239 SARs filed by non-depository institutions last year, compared with 560,996 in 2009.
At depository institutions, the largest concentration of SARs involved check fraud, 72,811 in 2010 compared with 84,952.
The next biggest category was mortgage fraud, 70,472, compared with 67,360 in 2009. There were 36,124 reports of credit card fraud, compared with 41,548 in 2009.
In 2010, there were 14,194 instances of consumer loan fraud, compared with 16,506 in 2009, the report said.
In 2010, there were 14,214 reports of wire transfer fraud, compared with 15,506 in 2009. Last year, there were 5,731 reports of debit fraud card, compared with 5,397 in 2009.
In 2010, there were 3,347 reports of commercial loan fraud, compared with 4,236 in 2009.