LONDON -- The FTSE 100 (INDEX: ^FTSE) perked up a bit yesterday to end the day on 6,558 points, but it has turned tail again today to fall 95 points, or 1.44%, to 6,464 by 9:30 a.m. EDT. Despite the apparent lessening of fears concerning the possible end of economic stimulus measures, a weak session in Asian markets led to a bearish opening in London. Until we get concrete updates on American and European monetary policies, the market looks likely to continue in this uncertain manner.

So which companies are leading the FTSE down? Here are three names that are slipping and look set to lag the index today.

Tesco
Tesco shares have fallen 4.6% after the U.K.'s biggest supermarket chain revealed a fall in like-for-like sales in its first-quarter update. In the U.K., we saw a 1% fall, but in other markets things were worse, down 3.8% in Asia and down a scary 5.5% in Europe (all excluding petrol sales). Total group sales were actually up 2.7%, but in like-for-like terms that translated to a fall of 2.2%.

The figures fell short of analysts' expectations, though chief executive Philip Clarke reckoned that Tesco had "broadly maintained [its] performance from the fourth quarter of last year." For the full year, forecasts suggest earnings per share falling 8%, with the shares now on a P/E of 11.

Thomas Cook (TCG)
Thomas Cook Group has managed a remarkable share-price recovery since its near-collapse the other year. But that recovery suffered a small setback today as the price dropped 12.4%. This morning saw 87.6 million new shares and 409 million nil-paid rights admitted to the market following the announcement of a placing and rights issue on May 16.

The firm also told us that nonexecutive director Richard Pennycook will step down after taking on the role of interim financial director at the Co-operative Group.

Glencore Xstrata (GLEN -0.15%)
The share price of the now-combined Glencore Xstrata has slipped 1.6% after the mining giant released an update about its final dividend. Although the payout is denominated in U.S. dollars, shareholders on the Jersey register will be able to take other currencies, and the sterling value has been set at 6.83 pence per share.

Over the past 12 months, the Glencore price has fallen 5%, though that's better than the prices of most other miners. But Glencore's shares are on a forward P/E of 12, which is toward the high end for the sector.

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