My top FTSE 100 'sells' for February

I reckon the next trading statement from energy colossus Centrica(LSE: CNA) -- currently slated for Thursday, February 23 -- could prompt a fresh downleg in the share price.

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The British Gas owner gave cause for cheer back in December when it announced the problems created by its slowly-eroding customer base had eased more recently. Indeed, Centrica commented that the number of accounts on its books was "broadly flat since the half year."

This will come as some relief to investors as Centrica has come under sustained bombardment from the steady rise of smaller, promotion-led suppliers in recent years. This phenomenon saw British Gas lose almost 400,000 in the six months to June 2016 alone.

But there's little sign that consumers' rising demands for cheaper utility bills are about to dissipate. Indeed, latest data from trade association Energy UK showed a record 4.8m households switched energy provider last year, up 26% from 2015 levels.

And 33% more people changed supplier in December, the body commented, one-in-five of which took their business to a smaller supplier.

Against this backcloth Centrica is finding it increasingly difficult to raise prices to generate profits growth. And Ofgem raised the stakes still further for the so-called 'Big Six' operators by commenting last week that it sees no "obvious" reason why recent rises in oil and gas prices should be passed onto customers in the months ahead.

Meanwhile, those anticipating a sustained uptick in fossil fuel values -- and with it a healthy revenues recovery at Centrica Energy -- could find themselves disappointed as rising US shale production and weak oil demand globally keeps the market oversupplied.

There are clearly many risks to the City's forecasts of a 7% earnings rebound at Centrica in 2017, a scenario that would end a predicted three annual dips on the spin. And I believe a forward P/E ratio of 13.9 times fails to properly reflect this.

Food for thought

I also reckon the earnings outlook is less than assured for supermarket struggler J Sainsbury (LSE: SBRY).

The London business surprised industry analysts earlier this month after announcing a rare improvement in like-for-like sales, up 0.1% during the 15 weeks to January 7. The news has sent the share price of Sainsbury's to levels not seen since last spring.

But recent figures are clearly far too weak to suggest Sainsbury's is over the worst. And on top of this, the retailer's recent sales uptick still trails the recent performances of its mid-tier rivals. Tesco and Morrisons saw underlying revenues rise 0.7% and 2.9% respectively in the weeks surrounding the festive season.

Clearly Sainsbury's still has its back to the wall as competition in the grocery sector heats up. And I believe signs of this stress in the firm's next trading statement (slated for Thursday, March 16) could prompt investors to hit the exits once more.

Given the possibility of escalating sales woes, particularly as rising inflation heaps pressure on consumers' spending power, I reckon a forward P/E ratio of 13.1 times isn't cheap enough to make Sainsbury's an attractive contrarian pick.

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