Is it? Isn’t it? The start of a strong recovery, that is. Who am I talking about? Mega miner Rio Tinto (LSE: RIO).

Rio’s share price crashed by 64% between July 2011 and 20 January this year. Since then though, we’ve seen a 29% recovery to 2,030p, on the back of an uptick in the prices of some key commodities — iron ore, copper, aluminium and gold have all regained some lost ground.

But there’s still a 47% fall in earnings per share (EPS) expected this year, leaving the shares on a forward P/E of 22 — and even a 45% EPS recovery mooted for 2017 would only drag that down to 15. Considering the major uncertainties over Chinese demand for the next couple of years, those currently banking on a sustained recovery might be taking too much of a risk.

Forecast dividends are still strong, but they’re falling and will almost certainly need to be cut if the hoped-for recovery hasn’t really started yet. There’s also the small matter of Rio Tinto’s debt — at the end of 2015 the firm was carrying net debt of $13.8bn (although that was a little better than a year previously). I’d like to see some dent in that before I’d be confident, together with a sustained improvement in commodities prices for a few months.

Oil back on track?

I’m particularly pleased to see Premier Oil (LSE: PMO) shares up 179% since trading resumed after January’s suspension — it means I’m now only around 35% down on my investment after an early 75% drop. At 53p, the shares are still down nearly 90% over five years mind, and the recent uptick has been for two reasons.

The price of oil broke above $40 per barrel a few days ago for the first time this year, from under $30 in mid January — as I write, a barrel of Brent Crude is going for $40.28. The firm’s acquisition of the whole of E.ON’s North Sea assets for $120m (which was the reason behind the suspension of the shares) also gave the price a boost, with investors impressed that Premier was able to snap up cheap assets while they were available.

The big downer still is Premier’s debt of $2.24bn, although plans are afoot to reduce it. Is Premier Oil back to winning ways? I do hope so.

Groceries success?

I’m less optimistic about Ocado (LSE: OCDO), the internet shopping company that ‘s also behind Wm Morrison‘s online offering, and whose shares are down 44% since their July 2015 peak to 263p. The company took a few years to turn its first profit, which it achieved in 2014 and followed it by a stronger 2015. We now have EPS rises of 36% and 57% forecast for this year and next, respectively.

But that puts the shares on a forward P/E of 100 for 2016, dropping to 64 a year later. And while such high multiples can be common when a new company is just getting going, I’m really not sure Ocado can generate the earnings levels needed to get down around the long-term FTSE average P/E of nearer 14.

Morrison’s deal with Amazon won’t help, and there are rumours that new chief executive David Potts wants out of the Ocado deal as soon as possible.

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Alan Oscroft owns shares in Premier Oil. The Motley Fool UK owns shares of and has recommended 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.