The changing makeup of gold investment makes the metal more vulnerable to steep losses if sentiment toward the metal sours, the managing director of commodities research at Barclays Capital said Thursday.

While the introduction of physically-backed gold exchange-traded products has been a key driver in gold's recent bull-run, this development could also undermine the metal if the opportunity cost of holding the metal rises, Kevin Norrish told the S&P GSCI Commodities Seminar in London.

"You now have a very sophisticated investor base with very large positions, so when things start to change, you could start to see a lot of gold dumped on the markets," he said.

"When the opportunity cost turns negative, you could see a problem," he added.

Nevertheless, rising opportunity costs remain some time off, and Norrish maintained Barclays Capital's view that the metal will trade above $2,000 a troy ounce next year.

In a widely-anticipated policy announcement late Wednesday the U.S. Federal Reserve said it will implement "Operation Twist," a move aimed at making credit cheaper and spurring spending and investment.

The measure is also designed to pressure interest rates in the long term, a boon for gold, which does not accrue interest and is cheaper to store when rates are low.

-By Francesca Freeman, Dow Jones Newswires; +44 (0)20 7842 9412; francesca.freeman@dowjones.com