Energy shares are firmly lower in pre-market trading as crude oil futures fall to trade below $99 a barrel. Stocks in the sector are weighed by investor concern over the effects of the earthquake in Japan at the end of last week and the potential crisis with nuclear facilities hit by the disaster. SunPower (SPWRA, SPWRB) says Japanese suppliers have indicated that, while certain operations are currently disrupted due to infrastructure issues, they have not sustained major damage to their facilities. Sunpower shares are up 2% in pre-market trading. Meanwhile, Madison Williams reportedly downgraded TransAtlantic Petroleum (TAT) to Accumulate from Buy. The firm cited relative valuation.