Gold continues to rise in price as the dollar declines and that is propelling mining companies higher. Gold miners, such as Randgold Resources and African Barrick Gold, are higher while other miners, such as Xstrata and Antofagasta, are hoping that there will be more stimulus measures for the global economy. The only one of the top risers not involved in mining is Imperial Tobacco. Imps assured the market it is still on track to meet forecasts for the year, even though growth in tobacco revenues has slowed slightly over the last six months.Insurer Aviva has gone ex-dividend today, although it has fallen much further than the 9.5p a share dividend warrants. Oil services provider Petrofac is the other Footsie company going ex-dividend today. Petrofac is paying a 13.8 cents a share dividend but the share price fall is more than three times that figure. RBS has changed its stance on pump maker Weir from buy to hold, even though it has raised its target price from 1412p to 1567p.FTSE 100 - RisersFresnillo (FRES) 1,225.00p +2.42%Xstrata (XTA) 1,195.00p +2.36%Randgold Resources (RRS) 6,455.00p +2.30%African Barrick Gold (ABG) 599.50p +2.22%Antofagasta (ANTO) 1,202.00p +2.12%Rio Tinto (RIO) 3,639.50p +1.95%BHP Billiton (BLT) 1,994.50p +1.81%Imperial Tobacco Group (IMT) 1,925.00p +1.69%Kazakhmys (KAZ) 1,423.00p +1.64%Lonmin (LMI) 1,697.00p +1.50%FTSE 100 - FallersAviva (AV.) 402.00p -3.60%Weir Group (WEIR) 1,389.00p -3.54%Autonomy Corporation (AU.) 1,770.00p -3.23%Resolution (RSL) 230.70p -3.11%Petrofac Ltd. (PFC) 1,372.00p -2.56%Tullow Oil (TLW) 1,263.00p -2.32%WPP Group (WPP) 716.00p -1.85%BP (BP.) 407.50p -1.76%Invensys (ISYS) 286.20p -1.75%Prudential (PRU) 608.50p -1.70%