i doubt if you are able to get the data but the number and business due to lost client can be used to measure reputation risk for instance you might take, the number of accounts closed,the decrease in deposit/lending following sanctions etc

Check the following:

Corporate reputation and social performance: The importance of fit

SJ Brammer, S Pavelin - Journal of Management Studies, 2006

Measuring reputational risk: The market reaction to operational loss announcements

J Perry, P De Fontnouvelle - Available at SSRN 861364, 2005

Managing reputational risk: curbing threats, leveraging opportunities

J Rayner - 2004 - books.google.com

Operational risk and reputation in the financial industry

R Gillet, G Hübner, S Plunus - Journal of Banking & Finance, 2010 - Elsevier

A good example of Reputation Risk is that of News Of The World - tabloid paper closed due to massive phone hacking scandals in UK in 2011  to avoid massive regulatory sanctions. As for financial institutions, Reputation Risk is usually monitored by both individual institutions and regulators as the said industry has capability of crippling entire economy. Having said and done as per above, depositors and borrowers are not likely to leave a bank due to emergence of negative information at least in short-term. It can therefore be regarded as low to medium in short-term otherwise depositors would have bolted from bailed out banks in 2008 Global Financial Crisis.