Singapore ? Oil prices fell to 4 1/2-year lows today in Asia as investor pessimism over global crude demand outweighed OPEC’s largest-ever production cut.

Light, sweet crude for January delivery was down 15 cents to $39.91 a barrel in electronic trading on the New York Mercantile Exchange by midday in Singapore. At one point, it fell as low as $39.19 — a level not seen since at least July 2004.

Overnight, the contract fell $3.54 to settle at $40.06 a barrel, after touching $39.88.

The 13-nation Organization of Petroleum Exporting Countries, which accounts for about 40 of global oil supply, said Wednesday it planned to reduce its output quotas by 2.2 million barrels a day.

But markets had already expected a vastly reduced flow of oil and traders focused instead on troubling economic data that points to a long and severe global economic slump.