Stock futures are pointing to a slightly lower open for major indexes on Wednesday as investors respond to a slew of earnings reports from retailers and brace for a big speech later in the week by Federal Reserve Chair Jerome Powell.

Traders appeared more certain that the Federal Reserve will cut interest rates at its monetary-policy meeting next month as Fed Chair Jerome Powell delivered remarks Friday at the annual Jackson Hole Economic Policy Symposium in Wyoming.

Stock futures are down on Aug. 20 as investors await Fed meeting minutes and key earnings from Target and Lowe's. See the latest market moves

Fed minutes are due, and top retailers will report earnings in the coming week. But the main attraction will be Jerome Powell's speech on Friday.

BEIJING, Aug 22 (Reuters) - Prices of lithium carbonate futures in China slid by more than 3% on Friday to hit their lowest in two weeks. The most active lithium carbonate futures on the Guangzhou Futures Exchange touched the lowest level since August 8 at 78,720 yuan ($10,957) per metric ton.

The final grand slam of the year begins this week in New York. Taft Gantt went up 18 units last month at Wimbledon and now gives his best bets for the U.S. Open

Prices this month have risen more than 30 per cent to above US$12,530, before paring monthly gains to around 21 per cent as of Thursday.

By Julie Ingwersen and Karl Plume CHICAGO (Reuters) -In a head-to-head contest in a small corner of agricultural futures markets, a legacy spring wheat contract that has traded for more than 140 years is fending off a challenge from a competing contract launched this spring by CME Group,