BOSTON (TheStreet) -- Billionaire investor George Soros' hedge fund made a big bet on Delta Air Lines (DAL - Get Report) in the fourth quarter, while keeping gold as its largest holding. Apple (AAPL - Get Report), maker of the iPad and iPhone, remained a top 10 position.

The fund, which serves wealthy investors, added 11 million shares to its Delta Air stake, bringing it to 14.7 million shares worth about $186 million, Soros Fund Management said in a Securities and Exchange Commission filing.

The fund's assets rose about 15% in the fourth quarter, to $7.7 billion, up from $6.7 billion on Sept. 30.

Despite having called gold a "bubble" investment in the past, Soros' fund added to its horde of the yellow metal in the fourth quarter. Gold is often considered a hedge against inflation and protection against a falling dollar. Commodities such as gold tend to be uncorrelated to the movements of stock and bond markets and so may serve as portfolio-diversification tools.

The SPDR Gold Trust ( GLD - Get Report), a gold-backed exchange traded fund, remained the largest fund holding at $655 million in the fourth quarter, up by about 25,000 shares over the course of the three months. This year, its value is off 4% after gaining 29% in 2010, when the S&P 500 Index rose 15%.

>>View George Soros' Portfolio

The fund's fifth-largest holding is also pure gold, Novagold Resources ( NG), a Canadian gold miner, at a $184 million allocation. The number of shares owned was unchanged in the fourth quarter.

Novagold is a rollercoaster stock, up 317% in 2009, up 133% in 2010, and down 7% this year.

Among the other top 10 holdings of the Soros Fund in order of size are: agricultural products giant Monsanto ( MON), U.S. oil and gas exploration firm Plains Exploration and Product ( PXP), generic pharmaceuticals maker Teva Pharmaceuticals ( TEVA) and health-care claims manager Emdeon ( EM).

The following are three stocks that Soros added to in the fourth quarter:

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Delta Air Lines ( DAL - Get Report), after its Northwest Airlines merger, is now the world's largest airline. It looks like the Soros fund thinks this company can dominate its industry.

For now, at least, major U.S. airlines are seen benefiting from the recovering economy and airfare hikes.

A Morningstar analyst recently wrote that "Delta's merger with Northwest (in 2008) could yield as much as $2 billion in annual network and cost synergies, which should help significantly alter the firm's cost structure going forward."

"We think Delta has the potential to deliver the best financial improvement among its legacy peers," wrote analyst Basili Alukos in a Jan. 20 research report.

Standard & Poor's analysts give it a four-star "buy" rating, one of the firm's highest ratings, and a 12-month price target of $16, about a 34% premium to the current price.

"We think industry-wide capacity cuts taken over the past two years will help drive airfare increases and yield improvement," write the S&P analysts. "We also see improvement in demand for corporate and premium travel as the global economy recovers from a protracted downturn."

Delta shares' performance are typical for the highly cyclical airline industry, up 11% in 2010, and down 7% this year.

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InterOil ( IOC) saw a 10% increase in the Soros fund's investments in the fourth quarter. The fund held a 4.4 million share position valued at $320 million on Dec. 31.

InterOil, with a $3.3 billion market value, is a Canadian oil and gas company with rights to properties in Papua New Guinea and the surrounding region, and has service and supply contracts with many of the world's largest oil firms.

After a spectacular 459% return in 2009, it has lost 10% in the succeeding period.

The Soros fund isn't the largest investor in InterOil, even with a 10% stake. Wells Capital Management has 12% of its shares.

Thomson Reuters says the analysts it polled give its shares two "strong buy" ratings, three "buys" and one "hold."

Their mean consensus price target over the next 12 months is $104, about a 40% premium to current prices.

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Soros doubled its position in the biotechnology firm Dendreon ( DNDN) in the fourth quarter to 4.2 million shares, worth about $147 million.

The company, with a market value of $5 billion, has one marketed product, the prostate cancer treatment Provenge, which is the first active cellular immunotherapy for cancer on the market, says Morningstar. "Dendreon also has other oncology immunotherapies and small-molecule drug candidates in preclinical and clinical development."

Thomson Reuters says analysts' consensus is for a loss of $2.95 per share in fiscal 2010, rising to a loss of $1.69 in 2011.

Those same analysts give the company eight "strong buy" ratings, five "buys," six "holds" and one "sell," Thomson Reuters says.

Its shares are little changed this year after gains of 474% in 2009 and 33% in 2010.

The company has 68% institutional ownership, led by Fidelity Investments.

Disclosure: TheStreet's editorial policy prohibits staff editors and reporters from holding positions in any individual stocks.