Number of 401(k) millionaires just jumped by 9.5% | Money [Video]

(CNN) — A new analysis by Fidelity Investments, one of the largest providers of 401(k) retirement plans, found that the number of accounts with balances topping $1 million rose by 9.5% in the third quarter.

All told, of the roughly 24 million participant accounts in the 401(k) plans for which Fidelity serves as record keeper, 544,000 of them had balances over $1 million, up from 497,000 in the second quarter.

The average balance in that group was $1.616 million, up from $1.595 million in the prior quarter.

Among Gen Xers — who are next in line for retirement — those who have been saving for at least 15 years had an average balance of just under $600,000, up 6% from the quarter before, according to Fidelity data.

And it found that the average balance for all participants who were saving for five, 10 or 15 years rose during the quarter.

The growth was due not …