LONDON -- Another day, another record -- that's how it seems to be for the FTSE 100 lately. And today is no exception, as the index of top U.K. shares broke through the 6,800 barrier for the first time since the dot-com madness at the start of the century. We have seen strong company results lately, but is the optimism premature? Considering we're not out of the economic woods yet, things might be getting a bit too overheated just now.

But whatever the reasons for the mini-boom, let's take a look at three individual companies setting their own new records.

Shares in BP ended yesterday on a 52-week record close of 477.7 pence and are slightly up on that at 482 pence at the time of writing. Over that period, the price has gained about 20% as the oil and gas giant emerges from the Gulf of Mexico disaster -- although the oil spill is still weighing on the company, as the full extent of the clean-up costs are as yet uncertain.

Based on forecasts for the year to December 2013, BP shares are on a price-to-earnings ratio of nine, and the expected dividend of about 24 pence (which should be more than twice covered) would provide a yield of 5.3%.

Mark & Spencer (LSE:MKS)
Yesterday's full-year results sent Marks & Spencer Group shares to a new 12-month record price of 470 pence, and today they're up another 1.8%, even though the high-street stalwart reported falls in pre-tax profit and earnings per share. However, the annual dividend was maintained at 17 pence per share. After the hike, M&S shares are up about 35% over the past year.

The shares are now on a trailing P/E of 16, which is a little above the FTSE's long-term average of about 14, suggesting that there is some confidence in M&S' recovery. Forecasts for 2014 drop the P/E to just less than 14 and suggest a dividend yield of about 4%.

easyJet (LSE:EZJ)
Most FTSE 100 companies can only dream of a 150% share price rise over the course of a year. But that's just what happened to easyJet after the budget airline's share price hit a 52-week record of 1,280 pence today. Last week's interim report, which showed revenue rising by 9.3% and the expected winter loss falling by nearly half, provided the latest boost.

With earnings growth of about a third forecast for the full year, the shares are on a forward P/E of 15, which seems perhaps reasonable for a growth share -- but airlines can be risky investments.

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Alan Oscroft has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.