LONDON -- In today's early morning trading, the FTSE 100 (INDEX: ^FTSE) dropped 39 points, but it has recovered a little to 5,652 at the time of writing -- just 13 points down. The mood seems to be a mix of vague optimism over Europe and general fear of a worldwide economic slowdown. And ahead of the forthcoming interim reporting season, nobody really knows what to expect.

But it's companies that drive the index -- not the other way round. Here are three constituents of the FTSE indexes that have been falling today.

Burberry (LSE: BRBY.L)
Shares in fashion purveyor Burberry Group fell by 5.8% to 1,209 pence after a first-quarter update showed slowing global growth. Though underlying revenue grew by 11% to 408 million pounds, that's down on last year's fourth-quarter growth of 15% and short of City expectations.

The firm saw a strong growth in men's tailoring and accessories and also benefited from higher prices. But in tough market conditions, it wasn't enough to satisfy the growth expectations in the share price, which is down nearly 25% since its April peak of 1,586 pence.

Britvic (LSE: BVIC.L)
Soft-drinks maker Britvic fell heavily this morning, dropping 14% to 259 pence after updating us on last week's recall of two of its Fruit Shoot products. There are problems with a new cap design, and the firm is going back to an old cap. The commencement of resupply is going to take six weeks, but it will take six months to get back to full volume.

The firm believes this will impact pretax profit to the tune of 15 million pounds to 25 million pounds over this trading year and next. Assuming the worst case, the recent 30% share price drop will put the shares on a forward price-to-earnings ratio of about nine for September 2012, which suggests the fall might be overdone.

Thorntons (LSE: THT.L)
Thorntons shares dropped 4.6% to 24.8 pence, despite a fine-looking fourth-quarter trading update. Trading at the chocolate and confectionery maker was in line with expectations, with sales growing by 7.8% to 24.7 million pounds. That was strongly boosted by a more than tripling of commercial sales from 2.9 million pounds to 9.3 million pounds, due to the introduction of a "Best of British" range for the summer -- but maybe investors are seeing that as a one-off.

Thorntons shares have lost more than 50% over the past 12 months.

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