Shareholders of Rio Tinto (LSE: RIO), Aviva (LSE: AV) and Tullow Oil (LSE: TLW) will surely have become sick of red arrows day after day in their brokerage account over the past year. But is there light at the end of the tunnel for investors in these shares?

Mining giant Rio Tinto’s annual results may have included an $860m full-year loss, but the biggest news was the suspension of progressive dividend payments. Shareholders are still forecast to receive some $2bn in dividends this year, roughly 110 US cents per share, but this will pale in comparison to the $6.1bn returned to them in 2015. Income investors will decry this news, but it’s undoubtedly in their best interests over the long term.

Savings from the slashed dividend, $3bn in capex reductions through 2017 and an additional $2bn in operating cost reductions will allow the company to keep debt levels manageable. Gearing for the past year increased to 24%, but this is far better than most competitors and will be sustainable even if prices of key commodities remain low.

Rio’s relative lack of diversification has been instrumental in maintaining free cash flow as its low-cost-production iron ore assets are proving profitable even at today’s depressed prices. Rio shares may not skyrocket any time soon, but the company has maintained a healthier balance sheet than competitors and has fewer high-cost assets to offload. Given these advantages, Rio could be a smart bet for long term-investors seeking exposure to the commodities sector.

A barrel of woes

Unsurprisingly, independent oil producer Tullow Oil also reported significant losses for 2015. Post-tax losses were $1bn as revenue fell 27% year-on-year. More worryingly, net debt rose 30% to $4.2bn, sending net gearing up to 56%. Tullow retains $1.7bn in cash and undrawn credit lines, but this level of debt doesn’t bode well for the shares quickly moving upward even if crude prices rebound significantly over the medium term.

On the bright side, the large TEN oil and gas field in Ghana will come online mid way through 2016, adding some 35k barrels per day of production. With TEN-related capex nearly finished and these additional barrels, operating cash flow will increase significantly. However, the company’s cumulative assets are only break-even in the $38 to $45/bbl range. At current prices the company will be pumping oil at a loss simply to keep cash flowing to operations while still adding to the mountain of debt.

Stability… at a price

Insurer Aviva offers the most stability out of these three shares, but also the least upside. Shares may be trading at a very low nine times forecast earnings and offer a 4% yield, but growth potential is very low. Government changes to pensions that no longer mandate lifetime annuities have hit one of Aviva’s most profitable segments hard. Furthermore, low interest rates on government bonds are also crimping the insurer’s ability to meet payments to customers without moving into riskier assets such as equities or corporate debt. Despite an attractive valuation and a relatively good dividend, I believe competitors such as Prudential offer significantly more upside potential.

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