LONDON -- The FTSE 100 (FTSEINDICES:^FTSE) has so far reversed yesterday's fall, picking up 1.9% to reach 6,401 by 10:25 a.m. EDT. This puts it above last week's close of 6,287, somewhat ironically boosted by weaker European data that strengthened hopes for further stimulative economic policies, with some suggesting even further cuts in interest rates by the European Central Bank.

But which companies are beating the index of top U.K. shares today? Here are three that are doing just that.

First-quarter results sent ARM Holdings shares up 11.2% to 967 pence after they had been sliding back since the beginning of March. Revenue for the three months to March 31 was 28% higher in sterling terms than in the same period last year, amounting to 170.3 million pounds. With a stronger operating margin of 50.5% (up from 44.5%), normalized pre-tax profit was boosted by 44% to 89.4 million pounds, while earnings per share rose 58% to 5.31 pence.

For the full year, we were told, "ARM has made an encouraging start to 2013 with more leading companies choosing to deploy ARM technology in their products and we therefore expect group revenues for the full-year 2013 to be at least in line with current market expectations."

Rolls-Royce (LSE:RR)
Shares in Rolls-Royce Holdings have picked up 4.1% to 1,159 pence after the aero engine maker announced the sale of its interest in the RTM322 helicopter engine program to Safran subsidiary Turbomeca. Rolls-Royce currently owns 50%, which will now be transferred in its entirety, in stages over the next three years, to Turbomeca, which will take on full ownership of and responsibility for the project.

Rolls-Royce will receive a payment of 293 million euros for its stake in the RTM322 project.

Premier Foods (LSE:PFD)
A first-quarter update from Premier Foods has sent its shares up 4.2% to 74.5 pence, which is a welcome boost after a few months of falls. For the quarter ending March 31, the firm saw branded sales up 2.2%, with sales of what it calls its "Grocery Power Brands" up 3.5%.

Restructuring of the firm's bread business is apparently on track, with previously achieved savings of 20 million pounds in overhead costs bearing fruit.

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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.