Wash sale is a tricky one to monitor. Here are few of the approaches taken by companies i have seen in my career and also the gaps in those processes:

• For any “sell at loss”, block repurchase on all securities from that issuer  for a 30 day period- Gap in this approach is that it does not factor in “substantially identical” securities.

• For any “sell at loss”, block repurchase on all securities from that issuer and its subsidiaries for a 30 day period. – Gap in this approach is that all subsidiaries may not issue “substantially identical” securities.

• For any “sell at loss”, block repurchase on all securities that might be in the same line of business using their sector classification for a 30 day period. – Gap in this approach is that it is too restrictive and can do more harm than good to the portfolio. Certainly PM’s aren’t going to be happy. Glad this approach never made it past the drawing board on any companies i worked with

• Reviewing all trading activity in the account during a 30 day period to see evidences of wash sale – Gap in this approach is that this could be more manual than others.

• Putting up a soft warning for opposite transaction in the same issuer or its subsidiaries and also for issuers in the same sector and reviewing the positions alerting(overnight). This is my preferred method.