Capita shares had fallen more than 14% on Thursday after the outsourcing group issued its second profit warning in three months, and by midday on Friday they had lost a further 3%.
However, overall the market was up, with the FTSE 100 index rising 18.75 points to 6,950.30.
MedicClinic International was the biggest riser on the index, up 4.1%.
The FTSE 100 is on track to record five consecutive days of gains. Financial stocks have helped to bolster the market this week, but there were signs that this rally was coming to and end with Prudential down 2.5% and Barclays dropping 2%.
In the FTSE 250, shares in Euromoney fell 5.7% after Daily Mail and General Trust said it would cut its holding in the company to about 49% from 67%.
On the currency markets, the pound edged up 0.1% against the dollar to $1.2595, and rose 0.5% against the euro to â‚¬1.1913.

The three-week Between the Monuments project is researching the daily lives of Neolithic and Bronze Age residents at the Wiltshire site.
The dig is being led by The National Trust and Southampton and Leicester University archaeologists.
The National Trust said if it is a house they will have "hit the jackpot".
Spokeswoman Dr Nick Snashall said: "I could count the number of middle Neolithic houses that have been found on the fingers of one hand.
"This site dates from a time when people are just starting to build the earliest parts of Avebury's earthworks, so we could be looking at the home and workplace of the people who saw that happening."
The site being excavated is next to the West Kennet Avenue - a 1.5-mile (2.5km) prehistoric avenue of two parallel lines of stones - and was first discovered by archaeologist and businessman Alexander Keiller 80 years ago.
The team has spent three years researching his journals and drawings together with modern geophysical survey techniques to pinpoint the excavation area.
They have also discovered arrowheads, clusters of scrapers for working hide and plant materials, miniature flint saws and pottery.
Dr Snashall said: "It's quite astonishing, millions of people have visited this site over the years but few of them can have guessed what they were standing on.
"The finds have been coming up three or four at a time, in clusters. It's as if the people were sitting here working away making arrowheads, scraping skins and carrying out their daily tasks and then they just got up and walked away."
The FTSE 100 remained on track for its best week since July, but shares in Capita continued to fall.
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Archaeologists believe they may have found the remains of a house where people who built Avebury stone circle may have lived.