LONDON -- It's been a week of two halves for the FTSE 100 (FTSEINDICES: ^FTSE), as it slumped 133 points (1.7%) to a low of 6,387 on Wednesday on fears of "tapering" of economic stimulus policies. But when the Federal Reserve failed to deliver the dreaded announcement, the index of top U.K. stocks turned back up and ended Friday at 6,492 -- that's just 8 points down on the week, but it does mark the FTSE's third week of losses in a row. Which were the biggest individual movers? Here's a quick look.

Wolseley (LSE: WOS)
Rumors of a possible special dividend from Wolseley sent the plumbing and heating merchant's stock up 197 pence (6.2%) over the week, to end Friday at 3,354 pence. Business in the company's U.S. markets is strong, and according to UBS, which upped its price target to 3,500 pence, Wolseley apparently has around 200 million to 300 million pounds it could return to shareholders. That could amount to between 70 and 110 pence per share.

IMI (IMI -1.78%)
First-half results gave specialist engineer IMI a nice boost, with its price gaining 70 pence (4.9%) to 1,504 pence. Although revenue remained flat at 1,087 million pounds, operating profit was up 5% to 162 million pounds thanks to improvements in margins, and the interim dividend was lifted 8% to 12.8 pence per share. The company says it is optimistic about the second half, telling us it expects to "deliver good progress in 2013."

John Wood Group (WG 0.50%)
Energy-services company John Wood Group suffered a fall of 60.5 pence (6.9%) to finish at 822.5 pence, despite reporting better revenue and profits in its first six months and telling us it anticipates full-year results will be in line with expectations. The dividend was boosted by 25% too, to 7.1 cents per share. But the company did tell us that some project delays, and weakness in Canada, could present "challenges to growth in 2014," and that seems to be what did the damage.

Persimmon (PSN -1.67%)
Housebuilder Persimmon reported a 40% rise in underlying first-half profits to 135 million pounds, with the U.K. government's "Help to Buy" scheme getting more people back to the housing market. The company also said it is accelerating its plan to return surplus cash to shareholders -- 75 pence per share has already been paid, and 10 pence in advance of the next planned payment of 95 pence will be handed over in June next year. The result for the stock price? A fall of 55 pence (4.6%) to 1,133 pence, but it's still up more than 60% over 12 months.

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