LONDON -- The FTSE 100 (INDEX: ^FTSE) is up modestly today, gaining 12 points to reach 5,904 by 9:30 a.m. EST. The week has generally been positive for the index of top U.K. stocks, as it looks to be approaching its 52-week high of 5,989 points again.

But even if the index is having a good day, there are individual companies that are not. Here are three whose share prices are falling today.

Rolls-Royce (RR 3.80%)
Rolls-Royce Group is down 2.9% to 887 pence after warning that it might face prosecution in a bribery and corruption probe centering on dealings in Indonesia and China. Today's announcement told us that the aerospace engineer has passed information to the Serious Fraud Office, involving intermediaries in those countries and in "other overseas markets."

The company told us it is "too early to predict the outcomes, but these could include the prosecution of individuals and of the company." Rolls Royce also said it would fully comply with the investigations.

PZ Cussons (PZC -0.20%)
PZ Cussons has dropped a modest 1.4%to 355 pence on the release of a first-half trading update. We were told that things are pretty much in line with expectations but that difficulties in Nigeria have led to flat revenue -- but there has been an overall rise in profit of around 10%.

Today's price fall is really quite meaningless, and the shares are still up an impressive 18% since early October.

Falklands Oil & Gas (LSE: FOGL)
Falklands Oil & Gas shares continued their recent fall, dropping a further 1.8% to 29.2 pence, taking the drop to more than 50% since the announcement that the firm's recent exploratory Scotia well was a failure. Today's trigger was the confirmation of the end of the 2012 drilling season. The Leiv Eiriksson rig is now to be dismantled and transported to Norway.

Investors now have time to consider whether the shares are oversold while the company deliberates on its drilling program for next year.

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