Footsie is expected to climb higher in early dealings as US results continue to impress following the start of the earnings season.This year continues to "shape up well" for Rio Tinto, but the mining heavyweight today warned investors to expect further volatility in commodity prices on fears of a double-dip recession and concerns about Chinese demand. In a second quarter update, chief executive Tom Albanese said operations are close to capacity and markets for most products are strong and the overall long term demand outlook is positive.Budget pub group JD Wetherspoon reported a 1% rise in like-for-like sales in the 11 weeks to July 11 and said it was confident of a resilient future performance despite economic worries. Wetherspoon, which has recently been moving away from its traditional role as a pub to compete with the likes of Starbucks by selling takeaway teas and coffees, saw overall sales climb by 5.8%. It has opened 41 pubs so far this year and disposed of two.London Stock Exchange's decision to cut its dealing tariffs helped it increase market share in the core cash equities business, but meant a mixed performance overall in the last three months. "Market conditions remained variable in the first quarter, with new issue activity down on higher levels last year in terms of money raised and strong trading activity from market volatility in May contrasting with relatively lower levels in the remainder of the period. Trading across the group's platforms in early July shows similarly varied trading levels," the LSE said.