Target-date funds are the fastest-growing choice in the 401(k) market. These "set it and forget it" investments are raking in the assets for good reason: They make the initial decision easy, and then run on "autopilot" through the investor's timeline to retirement.
But something notable has been happening inside the autopilot funds: Two behemoths, Fidelity Investments and T. Rowe Price, have been making pretty big adjustments, resetting the funds to "manual" in a sense. And you can learn a lot about target-date funds by taking a closer look at the changes.
1. Competition is heating up
As of September, Fidelity, T. Rowe and Vanguard Group controlled more than $400 billion of the total $546 billion in target-date fund assets, according to Lipper. Yet their dominance shows signs of vulnerability. When such funds came to prominence in 2005, the Big Three companies controlled 84 percent of assets. That's down to 74 percent.
The erosion of Fidelity's leadership position has been especially pronounced. The company controlled 61 percent of target-date fund assets in 2005 and is now down to 32 percent.
Meanwhile, even as the Big Three's overall share of the market has fallen, Vanguard and T. Rowe remain at all-time highs, with 26 percent and 17 percent, respectively.
The result of more competition means that, for an industry that tends to innovate at a glacial pace, your autopilot investment may be changing course more than you'd expect.
(Read more: Pros and cons of target-date funds)