WilliamWatts

SAN FRANCISCO (MarketWatch) — Oil futures fell Monday, stretching their losing streak to a third session and hitting their lowest levels in more than five years on concerns over a surging U.S. dollar and nagging worries of growing oil supplies.

Light, sweet crude for delivery in February US:CLG5 fell $2.65, or 5%, to settle at $50.04 a barrel on the New York Mercantile Exchange. Prices traded as low as $49.77 a barrel earlier in the session.

The settlement was the lowest for a front-month crude contract since April 28, 2009. Prices have lost 7.5% over the last three sessions.

February Brent on London’s ICE Futures exchange UK:LCOG5  declined $3.31, or 5.9%, to end at $53.11 a barrel, the lowest settlement since May 1, 2009. Brent has lost 8.3% over the past three sessions.

The U.S. Dollar Index DXY, +0.41%  , which measures the U.S. unit against a basket of six major rivals, was up 0.3% on Monday, and it’s up nearly 2% already in 2015, building on a 2014 rise that was the largest yearly jump since 2008.

A rising U.S. currency makes dollar-denominated crude more expensive to users of euros, yen and other units.

The dollar’s rise also stoked worries about the eurozone, and talks of a potential “Grexit,” or Greece exit from shared European economy, have re-emerged. That could be more devastating than the collapse of Lehman Brothers in 2008, one economist warned.

On the supply front, two major oil producers, Russia and Iraq, “recently scaled up their oil production and oil exports to their highest levels in decades,” analysts at Commerzbank said in a note Monday.

“Even though the negative trends on the oil market will predominate in the short term, we regard the current price level as excessively low and expect to see prices stabilize soon,” the analysts said.

Market observers expect the global crude oversupply to hit 1 million barrels a day in the first half of 2015. Analysts at Simmons & Co. said Monday they expect the oversupply to continue in the second half of the year, albeit at a more moderate pace.

Overall, economic conditions that oil markets face have not changed, “which is eliminating buyers from even considering entering [long] positions,” said Jameel Ahmad, chief market analyst at FXTM.

Elsewhere in energy trading, gasoline for February delivery US:RBG5  fell 5 cents, or 3.6%, to settle at $1.3814 a gallon on Nymex. That was gasoline’s lowest settlement since April 1, 2009.

February heating oil US:HOG5  declined 4.7 cents, or 2.6%, to $1.7492 a gallon, its lowest since Sept. 29, 2009. Both gasoline and heating-oil futures have declined for three straight sessions.

February natural gas US:NGG15  fell 12 cents, or 4%, to $2.8820 per million British thermal units. That was natural gas’s lowest finish since Sept. 24, 2012.

Michael Kitchen in Los Angeles contributed to this report.