LONDON -- After a few good days of rises, the FTSE 100 (INDEX: ^FTSE) wavered short of the 5,700 level this morning, falling 15 points in early trading to 5,672. That's still up 31 points on the week, though, and follows on from a strong seven days last week, which saw the U.K.'s index of biggest shares throw off recent eurozone worries.

But a few individual downturns hit the FTSE indices today, partly driven by falling sentiment in the construction sector. We look at three early fallers.

Halfords
Halfords Group (LSE: HFD.L) dropped 19.9 pence, for a 9% fall to 209 pence this morning, after Barclays downgraded its price target for the shares. The new target of 350 pence is down from its previous level of 385 pence, but it's still way ahead of the current price, and it's still rated as "overweight" (which means "buy").

Still, any downgrade for a falling stock is usually met with selling-off, and coming after other City forecasts had been downgraded, the fears of an unsustainable dividend added to Halfords' woes. The shares are now down more than 40% over the past 12 months.

The fall puts the forecasted dividend on a yield of 9.5% now, so there's room for it to be cut but still leave a decent payout.

Carillion
A trading update from construction services company Carillion (LSE: CLLN.L) disappointed the market today, and the shares fell 11.5 pence (4%) to 271 pence.

The firm reiterated its belief that first-half revenues will be lower than in the same period last year but told us that trading is still in line with expectations and that it is on track to achieve full-year profit estimates.

But the statement did say that market conditions remain "challenging," which is usually good for a few pennies off the price, and fears of a U.K. construction slowdown have helped send the shares down 30% over the past year.

Interior Services
Interior Services Group (LSE: ISG.L), also in the construction business, saw its shares plunge 10.5 pence (7.7%) to 125 pence after its pre-close trading statement was released.

Similarly to Carillion, the firm told us that trading for the year has been in line with expectations released in January, but that margins in the U.K. have been hit by competition.

Current City forecasts suggest a dividend yield of more than 10%, but whether that is achievable or sustainable is something we shall have to wait to see.

Finally, if you're in the market for FTSE shares that should not provide nasty surprises, then "8 Shares Held by Britain's Super Investor" may be for you. In this free report, we've analyzed the 20 billion pound portfolio of legendary City fund manager Neil Woodford. Click here now to discover his favorite large caps with high dividends and steady growth potential. But hurry -- the report is free for a limited time only.

Are you looking to profit as a long-term investor? "10 Steps to Making a Million in the Market" is the latest Motley Fool guide to help Britain invest. Better. We urge you to read the report today -- while it's still free and available.

Further Motley Fool investment opportunities: