ING booked a gain of 455 million euros on the sale of its stake in ABN Amro, which was taken over last month by Royal Bank of Scotland, Fortis and Santander.
That gain helped offset impairments in real estate and private equity investments.
Analysts had forecast net profit of 2.2 billion euros, according to the average in a Reuters poll.
"The third quarter was marked by turmoil in financial markets as concerns about U.S. subprime lending triggered a liquidity crisis and a repricing of risk. Risk management protected us against the direct impact of this turmoil," ING Chief Executive Michel Tilmant said in a statement.
ING Chief Financial Officer John Hele told CNBC television that the lender and insurer expects to book a similar gain in the fourth quarter on the sale of its stake in ABN, as well as other investment gains.
"We also have a few other great investments that will also close in the fourth quarter, so we expect another billion euros of additional gains from our investments," Hele said.
ING's insurance business posted an underlying pretax profit of 1.29 billion euros in the quarter, compared with 996 million a year earlier and an average forecast of 1.46 billion.
In banking, pretax profit fell 2.4 percent to 1.1 billion euros, in line with analysts' expectations.
ING shares touched a two-month low on Monday ahead of the results. Citigroup added to woes for bank stocks worldwide with a warning it may face as much as $11 billion in writedowns on subprime related losses.
ING also said in a separate statement that Malaysia's Public Bank Berhad had agreed to exclusively sell ING insurance products in the region in a 10-year agreement.