BOSTON ( TheStreet) -- Since the start of the year, mutual fund investors' focus has shifted from gold to black gold as oil prices have topped $100 a barrel for the first time in three years.

Investors have piled into ExxonMobil ( XOM), Chevron ( CVX) and Schlumberger ( SLB), companies that were avoided last year before oil's spike this year.

ProFunds UltraSector Oil & Gas Investor ( ENPIX) is leading the mutual fund pack with a 22.5% return this year and a 62% gain over the past year. It's closely followed by a sister fund, ProFunds Oil Equipment Service & Distribution Investor ( OEPIX), which has risen 21.7% and 54%, respectively.

The S&P 500 Index has increased 2.4% this year, while the oil and gas sector, as tracked by Morningstar, is up 10.5%. The broader energy sector has jumped 14%, at least double that of other industries.

The top-performing funds are also chock-a-block with oil-patch stocks as the world's oil supplies are being challenged by Middle East political turmoil. Of the 40 best-performing funds on the list, almost all have "energy" or "oil and gas" in their titles.

Uprisings are spreading across the Middle East after mass protests in Tunisia and Egypt ousted their two, long-serving presidents and are continuing in Libya, Africa's third-largest oil producer.

Protests there are the first to put oil supplies at serious risk as many U.S. oil producers are withdrawing workers from the country and shutting operations, Goldman Sachs said in a research report Tuesday.

ProFunds UltraSector Oil & Gas Investor, managed by a team led by Todd Johnson, has a big bet on ExxonMobil, at 19% of assets. The fund also has two bond holdings in its top five investments as well as shares of Chevron and oil-exploration leader Schlumberger.

The top positions of ProFunds Oil Equipment Service & Distribution Investor aren't much different as it has Schlumberger as its top holding, at 24%, a couple of bonds, and two oil-field-services providers, Halliburton ( HAL) and National Oilwell Varco ( NOV) in its top five holdings.

The following pages highlight some of the top-performing funds and their picks.

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