Aegon's platform business has passed the £2bn assets under administration marker for the first time.
The company said this was "a major milestone" and the pace of growth had been "staggering".
The £2bn figure represents the combined assets on Aegon Retirement Choices and Workplace ARC, which offer an auto-enrolment service.
These are the company's main platform services as well as the assets on One Retirement, Aegon's simpler pension solution for advisers and their customers.
ARC is Aegon's platform for advisers and it offers a Sipp, Isa and general investment account.
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Lou Macari, Aegon's platform strategy director, said: "The platform business earned its spurs when ARC crossed the £1bn mark last October, but the pace of growth since then has been staggering. ARC has gone from concept to multi-billion platform in under four years, and we're very proud to have built a product so resoundingly well received by our customers."
He said new technology, innovation and efficiency lied at the heart of the rapid growth.
He said: "But the key is to ensure the end customer's needs are met, which requires fully supporting advisers and employers to offer the best possible pensions and investments.
"The advised market is absolutely crucial to our success, so I'm delighted that our decision to build the proposition with a shared experience in mind has worked so well."