Today I’m looking at the investment potential of three big-cap movers.

Supermarket strides

Grocery giant Sainsbury’s (LSE: SBRY) continued its recent heady run last week, a 4% advance from Monday to Friday meaning the supermarket has risen by almost a quarter during the past eight weeks alone.

Investor appetite has been stoked by waves of positive data surrounding the firm, and latest Kantar Worldpanel research kept this trend running — the chain saw sales increase 1.2% in the 12 weeks to March 27.

Still, I believe the firm’s shares are in severe danger of toppling from current 18-month highs. True, its decision to ditch ‘multibuy’ deals and massage custom through improved brand investment is clearly paying off at present.

But the business remains at the mercy of Aldi and Lidl, operators whose store expansion schemes are driving sales growth through the roof — revenues at these budget outlets rose 14.4% and 17.7% respectively in Kantar’s latest reported period.

These pressures are expected to push earnings 6% lower in the year to March 2017, resulting in a P/E rating of 13.5 times. While this multiple is certainly very decent on paper, I believe Sainsbury’s has a hell of a fight in front of it to get the bottom line moving higher again as the competition in-store and online intensifies.

Positive update

Fellow retail giant Marks and Spencer (LSE: MKS) also leapt last week following better-than-expected trading numbers, the British shopping icon’s shares adding 9% between Monday and Friday.

M&S advised that like-for-like clothing and homeware sales slipped 2.7% in the 13 weeks to March 26, a vast improvement from the 5.7% decline punched in the prior three-month period.

Elsewhere, new store openings at its food division helped power sales here 4% higher in the quarter. And improvements to its M& portal pushed online revenues 8.2% higher.

With its international operations also picking up momentum, I reckon there’s plenty for potential investors to get excited about, even if the firm’s fashion lines still require plenty of work.

The Square Mile expects M&S to enjoy a 5% earnings rise in the year to March 2017, creating a great P/E rating of 12.5 times. I reckon this represents brilliant value considering the retailer’s excellent long-term growth drivers.

Risky Randgold?

Precious metals play Randgold Resources (LSE: RRS) was also a standout performer between last Monday and Friday, the digger’s stock gaining in 6% value thanks to fresh erosion in the US dollar.

This factor propelled demand for greenback-denominated gold higher once again, the yellow metal shooting back above the $1,240 per ounce marker.

However, I believe the gold price recovery is built on shaky foundations. I expect the North American currency to appreciate in the months ahead as expectations of Federal Reserve rate hikes intensify. And still-soft physical gold demand raises further questions over the underlying strength of gold’s recent ascent.

The City expects Randgold Resources to enjoy a 24% earnings rise in 2016, resulting in a mega-high P/E multiple of 37.4 times. I believe such a reading is far too expensive given the murky outlook for precious metal values.

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Royston Wild 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.