Shares in UniCredit were briefly suspended from trading Monday on the Milan stock exchange due to excessive volatility, as Italy's biggest bank launched a capital increase.
The bank has lost nearly half of its market value in recent days after announcing it was seeking to raise euro7.5 billion ($9.7 billion) at a massive discount to the prevailing share price.
The bank last week set the price for the rights at euro1.943, which represented a 69 percent discount over the previous day's close. Shareholders can buy the new shares through Jan. 27.
Shares resumed trading at midday with their price down 8.3 percent at euro2.40.
UniCredit SpA is trying to raise capital to meet new European requirements for banks to boost their financial cushions against possible losses.
Italy's market watchdog authority, Consob, said it had started checking into the movement of UniCredit shares on Wednesday and Thursday, when shares were suspended due to volatility, with an eye to possible violations of Italy's new rules on short-selling.
UniCredit shares dropped some 10 percent Thursday before trading was halted with the bank's share price standing at euro4.86 ($6.29). On Wednesday, its share price slid 15 percent.
UniCredit CEO Federico Ghizzoni has said that such a "technical reaction" was expected, and remained optimistic that the capital increase would be successful.
Banks are an integral part of Europe's debt crisis because they hold government bonds. A default or steep fall in the value of government bonds could inflict heavy losses on banks and choke off credit to the European economy. That's why the regulatory authorities want Europe's banks to raise their buffers by $115 billion (149 billion) over the next few months.