The deal that had the Swiss National Bank commit to freeze the value of the Swiss Franc against Euro was about to expire anyway, but the decision by the bank to unlock the cap was really surprising. That itself isn’t something to disturb prepared ones, because the prepared ones are aware of the possibility of changes due to every possibly imaginable reason, but to the unprepared ones, it gave a huge blow. Even in their wildest dreams, they couldn’t imagine that the Franc would surge even up to forty percent against the Euro.
It was January 15th when the president ended the deal with the EU. The same day Alpari UK issued a statement that they hadn’t enter into insolvency, and that pairs with the Swiss franc will only be traded if they were “close only” at the time and that they will disable opening new positions. Bloomberg said that IG Group had lost about 30 million dollars, and FXCM said that they lost 220 million from assets worth 1.2 billion.
16th January…
On 17th January Marko Dimitrijevic announced closing of Everest Capital’s Global Fund, his largest hedge fund that managed 300million worth assets, while his other seven funds kept on with managing 2 billion dollars worth assets.
Bloomberg reported on 19th January that three banks lost around 400 million dollars by that time, namely Citi Group, Barclays Plc and Deutsche Bank AG.

reference:
http://www.forex.in.rs/what-happened-to-the-swiss-franc-in-january-2015/
http://www.forex.in.rs/swiss-franc-is-black-swan-situation-brokers-lost-money-in-january-2015/