It is similar to ambulance chasing. If you do not join, you will get nothing ... unless you sue Icahn on your own. If you do join, the amount you'll receive will likely be very low. You should go through the pamphlet they mailed to you and find the paragraph which indicates the expected payout per share. From that, you should have a good feel very quickly if it will be worth your time to provide the necessary info. Understand, whether you participate or not, the lawyers will be collecting their fat fees - which is why they are doing this. Also keep in mind, the amount each investor ultimately receives will be a function of how many participate in the class action. If very few decided to participate, the funds recovered will still be split among those who participated, and each would recover more.
In general, I do avoid these. However, there was one, maybe 10 years ago, with a very small company I had invested in. CEO basically lied giving out false information regarding the state of the business. I did have a good size investment in the company. About 2 years after I gave my info to the law firm handling it, I received 3 checks in the mail (one for each account I owned shares in), totaling almost $15,000 - essentially making me whole. So, there are situations where it can work out very well, but generally it won't be where you have lots of investors participating.
