When you join Alliant, you are not just an account number. Alliant Credit Union is a not-for-profit financial cooperative, which means that all of our members are also owners. Our members-first philosophy has always served us well. With over 80 years of history and more than $11 billion in assets, Alliant Credit Union is the largest credit union in Illinois and one of the largest in the nation. Our excellent online, mobile and phone banking services, combined with our full suite of competitive products, make banking simpler for our 450,000 members nationwide.