Commodities Index Could Lose 40%: Analyst

The price of a barrel of crude could lose another $20 and the broader commodity market could slump by a third as the recent downtrend is set to intensify, Phil Roberts, technical analyst from Barclays Capital, told CNBC.

"The commodity market is still very much pricing in a further slow down and the signs we're seeing at the moment suggest that the process is intensifying rather than diminishing," Roberts said while taking a technical look at the Goldman Sachs Commodities Index.

The GSCI, which tracks a broad basket of commodities including oil, wheat and lean hogs, could lose another 30 percent to 40 percent, according to Roberts.

(Watch Roberts' full interview above for his calls on the S&P 500).

Oil prices could make a run for $50, Roberts said as price of light, sweet crude dipped below $70 for the first time in 16 months on Thursday.

The price of crude had fallen 31 percent, month-to-date, at the time of Roberts' interview.