The short-term effects of the EU referendum are still being felt, and the early irrationality threw up plenty of bargains for keen-eyed investors. Here are three FTSE 100 companies that did well in August.

Sell… no, buy!

Associated British Foods (LSE: ABF) dipped sharply immediately after the Brexit vote, but it didn’t take long to recover — thanks to an 11% rise in August, today’s 3,086p price is actually 7.5% ahead of its pre-vote level.

A Q3 update on 7 July reported overall revenue up 3%, with 4% growth at constant currency, which was ahead of expectations. Primark was again the star, with 7% growth in sales over the period.

Is Associated British Foods a buy now? Sadly, I think not. As well as the August rise making it more expensive now, the problem is nothing to do with Brexit, and all to do with the share price performance in recent years. From a P/E of around the market average in 2011/12, the price has nearly trebled over five years to a prospective P/E of 30 today. Sure, earnings growth has been impressive, and it’s forecast to resume in 2017 after two years of stagnation, but I reckon that’s just too high a valuation.

Contrarian bank?

While the rest of the sector was recovering from the banking crisis, HSBC Holdings (LSE: HSBA) was shunned due to its exposure to China’s slowing growth. Now it’s the EU that’s hands-off, and HSBC is back in favour. The shares gained 15% in August, and are up 24% to 578p since referendum day — a period that has seen an 18% fall for Lloyds and an 8% drop for Barclays.

On a forward P/E of a modest 13 and with a dividend yield of nearly 7% forecast, is HSBC a steal? Unfortunately, I see HSBC’s attractiveness as largely illusory, and it’s exactly the same bank it was on 23 June with exactly the same structural problems. It’s disparate divisions are operating in a less-than-joined-up fashion, and the banks’ costs are too high — and where we should be seeing top-down control, we instead have what looks like a panic-driven attack on costs while revenues are falling.

I was previously keen on HSBC’s dividends, but I wouldn’t bank on them now as I now see them coming under pressure over the next few years.

Attractive turnaround

Fortunes at Kingfisher (LSE: KGF), the owner of the UK’s B&Q and Screwfix outlets, have certainly been on the turn — a slow couple of years could well have bottomed out on 6 July, and we’ve seen a 21% share price recovery since then, to 373p today, including a 10% gain in August alone.

A first-half update on 18 August looked good, although there were differences between performance in the UK & Ireland and in France — the former brought in a 7.2% rise in like-for-like sales at constant currency, with a 3.2% fall from the latter. Still, France was beset with industrial action, and Poland, Russia and Spain all saw gains for an overall 3% rise. Speaking of the referendum, chief executive Véronique Laury noted that “there has been no clear evidence of an impact on demand so far on our businesses.

The shares are on forward P/E multiples of 15-16 with dividend yields of around 3%, which looks distinctively average at best. But the business is highly cash generative, and Kingfisher is still buying back its own shares. It looks a decent long-term buy to me.

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Alan Oscroft owns shares of Lloyds Banking Group. The Motley Fool UK has recommended Barclays and HSBC Holdings. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.