(ShareCast News) - Shares in engineer Weir Group have slumped back on Thursday ahead of the company's pending demotion from the FTSE 100, losing some of the ground gained in the last two days.On Tuesday the shares hit a five-year low but then bounced back apparently due to Blackrock calling a bottom in the shares and snapping up a few more via a CFD, plus a firming of the oil price and a bullish Liberum note on Big Oil.Weir is due to issue a third quarter interim statement on 3 November, with some rumours circulating about fracking contracts, while analysts have mooted potential gains for the company to benefit from wider sector consolidation and a potential slowing in US oil production fuelling the need for its services.But a profit warning on Thursday by peer Rotork, which has seen some major project deferrals, was read across to others in the sector, as well as a JP Morgan downgrade of Hunting.Furthermore, said analyst Michael van Dulken at Accendo Markets, Weir's shares have also been sold on technical reasons, with a trendline of falling highs and resistance dating back to early June."The shares have again suffered at the hands of technicals with the 20-day moving average sending them back from 1,330p towards recent 1,220p lows, possibly dented by analyst downgrades to oil & gas sector price targets and uncertainty related to the Fed rate hike, an already strong dollar and global growth questions hampering the black stuff from making any helpful major recovery in the near term."