Today I am looking at three FTSE 100 (INDEXFTSE: UKX) stocks set for prolonged earnings pain.

Keep your ore out!

The chronic oversupply washing over its major markets makes Rio Tinto (LSE: RIO) a risk too far for savvy investors, in my opinion. The digger has seen earnings slip during each of the past two years, and a further 35% drop is currently expected for 2016. And I wouldn’t rule out further bottom-line troubles beyond this year.

Rio Tinto — like many of its peers — is steadily ramping up iron ore production, for example, and plans to raise a target of 330m–340m tonnes from its Australian operations in 2016 to 360m further out. And the company is intent on broadening production across the globe, having submitted a feasibility study for its gigantic Simandou iron ore project in Guinea just last week.

But with Chinese demand indicators continuing to worsen, fears are rising over who will snap up this excess material, which is a worrying omen for future iron ore prices.

With the company changing hands on a P/E rating of 17.3 times — well above the benchmark of 10 times indicative of high-risk stocks — I think investors should give Rio Tinto plenty of distance.

Power problems

Fears over commodity prices are also whacking the earnings outlook over at Centrica (LSE: CNA).

True, Brent crude values may remain stable just below the $50 per barrel marker at present. But like iron ore, concerns over economic cooling in Asia — not to mention the US — threaten to send the benchmark tumbling, in my opinion. And OPEC and Russia’s refusal to cease ‘black gold’ production is casting a further pall over fuel values for the near-term and beyond.

But the prospect of prolonged revenues troubles at Centrica Energy is not the energy giant’s only problem. Indeed, the steady rise of Britain’s independent suppliers continues to dent the profits prospects of its British Gas arm, and Centrica saw its retail customer base slide by a extra 224,000 customers during January-March.

The number crunchers expect Centrica to rack up a 12% earnings dip in 2016, resulting in a P/E rating of 13.3 times. And, like Rio Tinto, I believe the risks facing the power play far outweigh the potential rewards at current prices.

Sales struggle

The extreme market challenges facing Pearson (LSE: PSON) also makes it a gamble too far, in my opinion.

The media group saw underlying revenues sink 4% between January and March as the impact of contract losses in its critical US market weighed. But problems in emerging markets cast further problems, forcing sales at its Growth division to fall.

With trading difficulties expected to endure, the City expects earnings to keep on dragging and a 24% bottom-line decline is chalked in for 2016 alone.

And despite Pearson’s massive restructuring drive, I reckon a P/E rating of 15.3 times represents poor value given the heavy lifting still to be achieved.

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Royston Wild has no position in any shares mentioned. The Motley Fool UK has recommended Centrica and 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.