LONDON -- The FTSE 100 (INDEX: ^FTSE) went nowhere much today, falling just 20 points by the afternoon to 5,827 points, just a little below the four-month high of 5,860 it achieved last week. The rise, which was due largely to recovering banks and miners, looks to be faltering this week.

But despite the FTSE indices doing well, there are plenty of companies whose individual share prices are falling. Today we look at three that have been crushed in August, in the hope there might be some bargains to be had.

Cape
Engineering services contractor Cape (LSE: CIU.L) has had a bad month after announcing on Aug. 1 that its operations in the Far East and Pacific Rim regions were suffering. The shares are down 102 pence (34%) to 195 pence since closing July on 297 pence.

The shares had only just been recovering from a profit warning in May that had sent them crashing down 38%, from 324 pence to 202 pence, and suggests again the old adage that profit warnings come in threes -- we had previously seen a 29% fall in November when the firm warned of "margin pressures" and "project scheduling delays."

The shares have now lost 67% since their 2011 peak of 596 pence, so is this a knife worth catching? Well, the most recent forecasts put the shares on a prospective price-to-earnings (P/E) ratio of 10.6, and a dividend yield of 7.4%, so they might be cheap -- or do warnings actually come in fours?

Spirent
 Spirent Communications (LSE: SPT.L) has had a tough month, too, after a strong share price rise this year was brought to an abrupt halt on Aug. 2 when interim results caused a 24-pence (14%) fall to 144.7 pence -- and they've stayed at that level since, on 145 pence today.

The shares had piled up from a low of 106 pence in December to hit a 2012 peak of 174 pence in May for a 64% gain, and again hit 168.5 pence the day before the results. The reason for the fall is that, though the first six months of the year brought on a 9% rise in adjusted operating profits to $63 million and the dividend was lifted by 10% to 1.39 cents per share, second-half growth expectations were cut back. And a big fall is so often the result when optimistic growth expectations are tightened.

Petra
Shiny things, like gold and diamonds, were all the rage during the financial crisis, but the shine has worn off for Petra Diamonds (LSE: PDL.L), which has seen its share price crash by 21 pence (18%) to 98.7 pence this month, and by 48% since March's high point of 188.2 pence.

Though behind the world's largest diamond producers, DeBeers and Alrosa, Petra is sitting on a very large asset base, as described by Fool Tony Reading in September. And since then, we've had the company's migration from AIM to the main market, good interim results in February and third-quarter figures in May. Add to that a strong trading update on July 31, which told of a 98% increase in production volumes and a 44% revenue increase, and we could have a bargain. The only real problem looks to be the company's tumbling cash position, which has seen cash fall to $37.4 million from $325 million a year ago.

This Wednesday brings us the firm's guidance for 2013, and 2012 full-year results are due on Sept. 24.

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