Petra Diamonds Ltd's first quarter revenue fell by 17 percent after Tanzanian government last month seized consignment of diamonds from its Williamson mine.
Red Kite, the largest metals hedge fund in the world run by UK Conservative Party donor Michael Farmer, is alleging that Barclays Bank attempted to rig the copper market through insider dealings with the London Metal Exchange.
Ken MacKenzie defended CEO after attacks from activist investor Elliott Advisors prompted speculation that the end of Andrew Mackenzie's tenure was imminent.