Investors may get the heebie-jeebies just thinking about opening their quarterly mutual fund statements this month.

But it’s OK — tear into those fourth-quarter statements, because a pleasant surprise may await. The headlines were scary and the markets were volatile, but most fund investors made money in the fourth quarter.

“The quarter didn’t feel very good, because we got off to such a nasty start, and we didn’t end the period very well either,” said Christine Benz, editor of Morningstar FundInvestor, a newsletter for small investors. “But sandwiched in there was one heck of a rally.”

The stock market hit what seemed to be its bear-market bottom on Oct. 9, with the three major averages below their previous bear market lows of late summer. At that point, the Dow Jones industrial average had lost about one-third of its value since 2000, and the Standard & Poor’s 500 index had given up about half.

But after that plunge, the market spent the rest of October and much of November on a steep upward trajectory that restored 1,700 points, or 24 percent, to the Dow. The technology-laden Nasdaq composite index climbed an impressive 34 percent.

Stocks spent most of December in a serious funk — in fact, it was the worst December for the Dow since 1931 — and some of the quarter’s previous gains were trimmed, but the final tally was still positive. The average U.S. diversified stock mutual fund gained about 6 percent in the quarter, according to preliminary estimates from Lipper Inc., which tracks mutual fund performance.

This was a dramatic turnabout from the third quarter, when the average stock fund dropped 14.3 percent.

“The market was really sold out after Oct. 9, and no area was more oversold than technology,” said Larry Puglia, portfolio manager of the T. Rowe Price Blue Chip Growth fund. “We bought some of the beaten-down tech stocks in October, and that really helped us for the quarter.”

Puglia’s fund was up about 14 percent for the quarter, but stout gains were the norm with almost every mutual fund category posting good results. The average large-cap growth fund, one of the largest and most popular fund categories, posted a 4.8 percent gain. Even with that performance, however, this category still remains down 28.6 percent for the year.

Another popular category — large-cap value — gained 8.2 percent in the quarter, but like the growth category, it remains in negative terrain for the year, down 20.2 percent. Value stock funds typically buy slow-growing, more mature companies, while growth funds buy faster-growing, often more immature companies.

Bond funds also continued to post some respectable gains for the quarter, adding to the already stellar performance of the previous three quarters. For example, the average corporate bond fund gained about 2.6 percent in the quarter and is up 4.6 percent for the year, according to Lipper.

Michael Kennedy, manager of the Stein Roe Liberty Intermediate Bond fund, explained that falling interest rates have provided a nice tailwind for bonds, since bond prices rise as interest rates fall. At the beginning of the year, the benchmark 10-year U.S. Treasury bond was yielding 5.1 percent, but it has fallen to its current yield of 3.8 percent.

“The market finally realized that there was tremendous value in corporate bonds,” Kennedy said.

The best-performing category among all the diversified U.S. stock funds — which basically excludes international funds and so-called sector funds — was S&P 500 index funds, with an 8.2 percent gain.

The basic strategy of index funds — and there are more than 170 of them — is to invest in all the stocks of a given index, such as the S&P 500, the Nasdaq or even the Dow Jones industrial average.

No effort is made to try to select the best stocks, just all the stocks, and the portfolio managers typically invest all the cash that comes in.

Perhaps the quarter’s most dramatic recovery occurred in two of the sector funds — telecommunications and technology. Both categories were down more than 20 percent in the third quarter, but the average telecom fund soared 23.7 percent in the fourth quarter and the average tech fund was up 17.3 percent.