ING stands for International Netherlands Group. It is a big Dutch financial company offering all kinds of services (banking, investing, insurances, etc.).
A couple of years ago they were in the news when they took over Barings (resulting in ING Barings), after Baring ran into trouble with their Singapore (or Asian) operation thanks to Mr. Nick Leeson. BTW I don't believe that was a very succesful take over...

I use them for asset management (but not in the US) and they are a large and reliable company IMO.