Brokers downgraded Proton after it reported last Friday a surprise net loss of 60.1 million ringgit ($19.7 million) for the third quarter mainly due to larger turnaround expenses for Lotus.

By 0824 GMT, Proton shares were down 6.5 percent to 3.61 ringgit, a level not seen since September 24, 2009, while the benchmark stock index rose 0.6 percent to 1,500.70 points.

The national car maker bought an initial 64 percent stake in the British car maker in 1996 for about 38 million pounds, finally buying all remaining shares in 2008 effectively privatising the company.

Proton is expected to incur more expenses for the restructuring of Lotus, which will see a depletion of its cash holdings, OSK Research said in a note.

The continued focus on Lotus has worried analysts, who cut their recommendations and target prices on the stock.

CIMB and OSK downgraded the stock to "neutral" from "trading buy" and "buy" respectively, while HwangDBS, which maintained its "hold", cut its target price to 4.45 ringgit per share from 4.70 ringgit.

Four out of 14 analysts tracked by Thomson Reuters I/B/E/S have a "buy" call on the stock.

The analysts have a consensus net profit estimate of 228.5 million ringgit for Proton's full year.