Credit Suisse upgrades Tullow Oil, downgrades Ophir Energy

On the basis of the above, shares of Tullow Oil were lifted to 'outperform' (with a target price 210p, versus 205p previously) on valuation grounds and due to catalysts now lying closer on the horizon.

Cairn (CS's 'top-pick' with an unchanged target of 260p), Nostrum and Aker BP (target steady at 170p)were all kept at 'outperform'.

However, Nostrum's target was cut from 545p to 460p.

As a group, companies in the space were facing off against two challenges, worsening investor sentiment despite an improved oil price outlook and the need to position themselves operationally on the global cost curve relative to US shale rivals.

"International E&Ps are pricing in a long-term oil price of $57/bbl, on our estimates, vs. the forward curve at $54/bbl. Valuations have become more attractive compared to when we initiated on the sector," the Swiss broker observed.

Back in March, the stocks were discounting an oil price of $67 on average.

However, within the same report Credit Suisse also downgraded Ophir Energy from 'outperform' to 'neutral' (target price reduced from 100p to 85p) because of the delay to the final investment decision on the Fortuna FLNG project and Africa Oil to 'neutral' (target price cut from 18.5p to 13.0p) due to a more cautious view on development in Kenya.

Lundin and Premier Oil (target kept at 60p) were both kept at 'underperform'.