Today I am looking at two London stocks in danger of fresh share price problems.

Digger keeps diving

Despite enjoying a solid share price uptick in the latter part of January, mining giant Rio Tinto (LSE: RIO) still had a month to forget, with shares in the business falling 13%.

Further falls in the first two days of February have resulted in  Rio Tinto’s stock value collapsing 46% over the past 12 months, and more than 66% over the past five years. But I believe the worst is yet to come, as the rout across commodity markets is far from over.

Sure, prices of iron ore are now above the $40 per tonne marker, supported by a rare uptick in Chinese steelmaking activity. But the industry still continues to contract thanks in no small part to China’s weak construction sector, leaving iron ore in danger of falling below recent multi-year troughs around $38.30 per tonne.

Indeed, fresh swathes of bearish data from the commodities-hungry nation threatens to send prices across Rio Tinto’s other key markets south, too. Chinese manufacturing PMI for January came in at three-year lows of 49.4, data yesterday showed, and I expect further rounds of disappointing data in the coming weeks as monetary easing from the People’s Bank of China flounders.

The City expects Rio Tinto to announce a 51% earnings slide for 2015 when it makes its full-year statement on Thursday, February 11th.

Investors should be braced for a colossal dive lower, like that of BP on Tuesday, should even these poor forecasts miss the mark. But an even bigger peril for the share price comes in the form of potential dividend cuts.

Rio Tinto is anticipated to keep the full-year payment locked frozen around 215 US cents per share in 2015 and 2016, creating a prospective yield of 7.3%. But should the mining giant finally grasp the nettle to address its worsening earnings outlook and swelling debt levels, I would expect share prices to head through the floor.

Crude play under the cosh

Naturally, I also reckon fossil fuel producer Cairn Energy (LSE: CNE) remains on shaky grounds, also thanks to the worsening state of commodity markets. The business saw its share value dip 10% in January, and a poor start to February has seen Cairn Energy fall an eye-watering 31% over the past year.

And like Rio Tinto, the oil play is in danger of further weakness should supply/demand data continue to worsen. Indeed, US oil inventories are expected to stand at new record highs just shy of 500 million barrels when numbers are released later this week. And these are likely to keep rising as supply from across North America, Russia and the OPEC bloc swells.

The City expects Cairn Energy to clock up a third year in the red in 2015, and losses of 47.7 US cents per share are currently forecast. And additional losses are predicted for 2016 as massive operating costs and weak crude values weigh, this time by 16.9 cents per share.

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Royston Wild has no position in any shares mentioned. The Motley Fool UK has recommended Rio Tinto. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.