Fidelity Investments found that retirement account balances hit an all-time high in the third quarter, marking the fourth three month period in a row in which U.S. Americans saved move.

What’s more, the Boston investment firm found based on its quarterly analysis that on average 401k and IRA balances jumped 10% year-over-year, continuing to set new records.

“Two of the most important aspects of a retirement savings strategy are how much an individual contributes and how they allocate their savings,” said Jeanne Thompson, senior vice president, Fidelity Investments in prepared remarks. “The increasing use of target date funds, along with the increasing number of individuals contributing more to their retirement accounts, can help ensure people are saving at the right level and have a diversified mix of assets, which will put them on a path to reach their retirement savings goals.”

[Learn what brokers to trust with Investopedia's broker reviews.]

According to Fidelity Investments, the average 401k balance increased to $99,900 in the third quarter while the average IRA balanced increased to $103,500. Fidelity found that the account balances in IRAs and 401k plans increased for every generation during the last year but that there was “significant growth” among Gen X investors. Among those savers, the IRA balances increased 16.5% to $51,000 while it increased 18% for 401K balances to $98,800.

Some of that increase doesn’t come on the part of American’s putting away more money but is a product of a stock market that continues to march higher. The average 401k contribution rate increased 8.5% during the three months ended in September, which is the highest percentage in nearly ten years. More than one in four savers increased their contribution rate compared to last year, noted Fidelity. As for IRA investors, the amount contributed increased 12%.  Fidelity said it saw an increase in its Roth IRA for Kids, which the firm said hit 10,000 accounts during the September ended the quarter.

Another finding from Fidelity’s quarterly analysis of IRA and 401k savings is that an increasing number of employees are using target-date funds, which invests in stocks, bonds and cash based on the age of the person. As of the end of the third quarter, 29% of all Fidelity 401k assets are held in target-date funds, which is up 18% at the end of the third quarter of 2012. Nearly half of all workers hold all of their 401k savings in a target date fund, up from 30% five years ago.