LONDON -- After a shaky start to the week yesterday, when the FTSE 100 (FTSEINDICES:^FTSE) managed a modest 22-point gain, the index of top U.K. shares is looking a little stronger today. By 9 a.m. EDT the FTSE is up 0.85% to 6,384, with a bit of brightness in the financial sector giving it a lift. We're still quite some way from the 13-week high of 6,876 set on May 22, but the recent slide seems to have been halted -- at least for now.

Which individual companies are doing well today? Here are three FTSE 100 shares that are on the up.

When the market is so happy with you that your share price has more than doubled in 12 months, what do you do for an encore? Well, if you're easyJet, you could announce the purchase of up to 235 new planes. And that's what has driven shares in the budget airline up a further 2.6% to this morning, taking them up more than 150% over the year.

easyJet says it got a good deal from Airbus by ordering 35 current-model A320 planes, plus 100 next-generation A320neo aircraft, with delivery stretching from 2015 to 2022. And there's an option on a further 100 of the A320neo planes, too.

A first-quarter update from Whitbread has sent the shares up 2.9% this morning. The firm, owner of the U.K.'s Premier Inn and Costa Coffee chains, reported a 13.8% rise in total sales, with like-for-like sales up 3.1%. Costa brought in the biggest rise: 24.8% overall and 8% like-for-like.

The firm's restaurants lagged a little as the weather kept people at home, but in the last few weeks there has been some improvement. Whitbread shares are now up 60% over the past 12 months.

Some of our financials have been having a good morning based on positive sentiment, with analyst upgrades sending a few of them upward. One is HSBC Holdings, whose share price has picked up 2.6%. The price has been higher, having hovered around 770 pence, but we are still looking at a gain of more than 25% over the past 12 months.

And with the shares on a forward P/E of less than 10 and a dividend yield of 4.9% expected, there could be a fair bit more to come.

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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.