LONDON -- The FTSE 100 (INDEX: ^FTSE) is remaining robust, falling just 18 points to 5,604 by the middle of the day. It's 110 points up on the week. The strength seems largely due to rising hopes for a eurozone rescue and a collaborative approach to government borrowing and to assisting troubled banks.

But individual companies have their own trials and tribulations to face. Here are three names from various FTSE indexes that have slumped today.

Shares in Invensys (LSE: ISYS.L) put on a massive spike at the end of the day yesterday to finish 67 pence up to 270 pence -- that's a rise of 34%, and there was no apparent news. But it all became clear this morning with an equally rapid fall of 42 pence back to 215 pence for a 16% morning drop. It seems investors had gotten wind of takeover discussions and piled in, but the optimism was crushed before the markets opened when the firm confirmed there have been talks, but that they have been abandoned.

Shares in Aquarius Platinum (LSE: AQP.L) slumped 10% to 54 pence after the company released disastrous news of its Everest mine. Falling metals prices, coupled with poor ground conditions at the mine and ongoing industrial relations problems, mean that the South African operation is just not profitable. The mine is now to be placed on "care and maintenance" status until trading conditions improve. This follows the similar mothballing of other resources, though the company currently does not expect any further mine closures.

Meanwhile, in the FTSE 100, Yell Group (LSE: YELL.L) continues to see its shares punished. They're down a further 2.5% today, standing at just 1.32 pence. Over the past 12 months, Yell has lost over 75% of its value, and today it has a market capitalization of just 32 million pounds. With online search becoming increasingly dominated by the big operators and people turning to Google before anything else, Yell's attempts to capture the local online marketplace have not swayed investors in its favor.

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