[malandrew]

TBH, client details really should belong to both the firm and the traders, since at the end of the day those clients most likely will continue to execute trades with that trader regardless of what firm they work at. Back when I worked in finance, many traders I knew were hired based on the clients with whom they had a solid professional relationship.

The value of a trader to a firm is essentially their professional relationships with clients combined with the efficiencies and information provided by the firm itself. The trader needs information from the firm and his co-workers to effectively monetize his client relationships, but those relationships really are his/hers at the end of the day. It's not like a trader can leave a firm and some other trader can pick up those relationships right where the other trader left them off. They can try of course, but the relationships are likely to move from firm to firm with that trader.

The spreadsheet is also dubious grey area. Yes, it may be proprietary information created by the trader while at that firm, but it is just as likely to have been created by that trader before he joined the firm that he brought with him when he joined. The only thing that changes when a trader joins a firm is that he ceases to use inputs from the economists and analysts at his previous firm and now begins using the figures from the economists and analysts at his new firm. Proprietary models often are created by a trader and intelligible to that trader and only that trader, unless they happen to have trained a junior trader to understand the ins and outs of their own model.

I was one of the analysts myself and every single model created by any senior analyst was reused by their junior analysts, but was often scrapped anytime a new senior analyst who joined the firm to replace the previous senior analyst. When you have your name and reputation on the model and the investment advice, the tendency is to do a big rewrite.