With the price of oil having fallen heavily in the last year, it is perhaps of little surprise that Premier Oil’s (LSE: PMO) share price is 87% below its level from one year ago. Of course, the North Sea-focused oil producer’s shares are currently suspended due to the planned acquisition of E.ON’s North Sea assets for around $120m. However, for many investors in the company, the damage has already been done and their shares are worth just a fraction of the price paid for them.

Looking ahead, Premier Oil’s purchase of the aforementioned assets could prove to be a shrewd move. Certainly, North Sea operating costs are apparently higher than in many other regions of the world and this can make it a relatively uncompetitive region while oil prices are so low. However, it also offers stability and high quality assets and so remains an appealing place from which to produce.

Furthermore, the assets are being purchased from existing cash flow and the fact that Premier Oil is embarking on an acquisition strategy shows that it is thinking about the long run, rather than the short term. This viewpoint is crucial while oil prices are low since it should enable companies such as Premier Oil to become stronger relative to their peers in the coming years. And with Premier Oil having a more stable financial outlook than for many of its peers, it could prove to be a strong buy (post suspension) for less risk-averse, long term investors.

Also posting a significant share price fall in the last year is Petra Diamonds (LSE: PDL). Its shares have slumped by 59% in the last year and a key reason for this is a deterioration in the company’s financial performance. In fact, net profit fell on a per share basis by 32% in the last financial year and this trend is due to continue in the current financial year with a fall of 14% being pencilled in.

While such negative growth rates are disappointing, Petra Diamonds trades on a price to earnings (P/E) ratio of just 11.8 which appears to take into account the expected challenges which lie ahead for the business. These include the prospect of further falls in the price of diamonds, as well as the uncertainty which comes with the company’s ambitious expansion plans. In addition, the company’s financial standing remains in question after its lenders agreed to relax borrowing covenants last year. But with Petra set to increase production over the medium term, it could prove to be a strong, albeit risky, buy.

Meanwhile, shares in intellectual property specialist Intelligent Energy (LSE: IEH) have also fallen dramatically over the last year and are now down by 73%. In fact, they have fallen by 50% since the turn of the year even though the company has released positive news flow regarding its acquisition of the energy management arm of GTL, which provides energy to telecoms towers across India.

The £85m deal is now set to go through since India’s competition commission has cleared it. It has the potential to boost Intelligent Energy’s distributed power and energy division and also provide it with a customer base through which to sell its fuel cell technology. Despite this, investor sentiment in Intelligent Energy appears to be on the decline and therefore, it may be prudent to watch, rather than buy, the company right now since it could move lower.

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