SINGAPORE (Reuters) - Singapore stock market was headed for a second consecutive session of losses, weighed down by poor performance of SIA Engineering Co and palm oil companies, lagging behind a rebound in the regional market.

The benchmark Straits Times index was down 0.33 per cent at 3,088.3 as of midday, while MSCI's broadest index of Asia-Pacific shares outside Japan rose 0.9 per cent.

SIA Engineering Co was among the worst performers of the index as the stock shed 2.3 per cent to hit an intra-day low of $4.76, putting it on track to its biggest daily decline in one month.

Brokerage Maybank Kim Eng said weaker performance of Hong Kong Aero Engine Services, which is 10 per cent owned by SIA Engineering, has put pressure on SIA Engineering.

The brokerage maintained its "buy" rating on SIA Engineering, but trimmed its target price to $5.75 from $5.88 and FY2015-17 earnings by 2 per cent to 5 per cent.

Commodity firms fared poorly. Golden Agri-Resources declined 1.6 per cent to an intra-day low of $0.60, while Wilmar International fell 3.5 per cent to $3.35, its lowest in nearly three weeks.

Malaysian palm oil futures stretched losses into a second day on Wednesday, falling to a one-week low as profit-taking continued to weigh.