Q: I am in my mid-30s and I am hands off with my 401(k). Should I be more active with the funds my 401(k) is plugged into? – William E. Collier A: When it comes to 401(k) plans, inertia tends to rule—many people never revisit their initial investment choices after enrolling. It’s important to keep tabs on your plan and to make a few tweaks occasionally. But whether you should be a lot more active depends on how comfortable you are managing your own investments. Most 401(k)s offer low-cost core stock and bond funds, including index options. If you are familiar with the basic rules of asset allocation, you can easily build a diversified, inexpensive portfolio on your own. But recent research makes a good case that getting some professional help with your portfolio can boost returns. Pros may not outsmart the market, but they can often save your from your own worst instincts—taking too much or too little risk, or changing your investments too frequently. As a recent study by consultants AonHewitt and advice provider Financial Engines found, investors who followed their plan’s financial guidance earned median annual returns that were 3.3 percentage points higher than do-it-yourselfers, net of fees. The study analyzed the returns between 2006 and 2012 for 723,000 plan participants, including investors in target-date funds and managed accounts, those using the plan’s online tools, as well as do-it-yourselfers. A three percentage point gap is substantial. A do-it-yourselfer who invested $10,000 at age 45 would have $32,800 by age 65; by contrast, the average 401(k) saver using professional advice would have $58,700 at age 65, or 79% more, the study found. Another analysis by investment firm Vanguard found a smaller difference in returns for those who got help vs. those who didn’t. Target-date investors earned median annual returns of 15.3% vs. 14% for those managing on their own. The do-it-youselfers also had a wide range of outcomes, with the 25% earning median annual returns of less than 9%. These days more plans are providing guidance in the form of online tools and target date funds: 72% of 401(k) plans offer target-date funds, up from 57% in 2006, according to the Investment Company Institute. The Plan Sponsor Council of America found that 41.4% offered some kind of investment advice in 2013, up from 35.2% the previous year. Taking advantage of this help can be a smart move. But if you opt for a target-date fund, be sure that you use it correctly—as your only investment. Adding other funds will throw off what’s designed to be an ideal, all-in-one asset mix. Unfortunately, nearly two-thirds of target-date fund users put only some of their money in one, while spreading the rest among other investments. That move may lower your median annual returns by 2.62 percentage points, the study found, compared with investors who put all their money in a single target-date fund. If you decide to go it alone, make sure to build your own ideal portfolio mix—try Bankrate’s asset allocation tool. To minimize risk, rebalance once a year to prevent any one allocation from getting too far out of whack. As you near retirement, remember to ratchet down the risk level in your portfolio by shifting to more conservative investments, such as bonds and cash. Make these few moves, and you won’t get left behind by being hands on.