I hate admitting it as much as any advisor does. But not every stock works out, even Canadian Edge Portfolio recommendations I’ve pored over for years. My goal is to not become emotionally committed to any one stock and therefore remain capable of moving on should events turn against that company.

Unfortunately, over the past month three Portfolio Holdings have experienced developments disturbing enough to merit a change in advice. First, I’m selling Conservative Holding CML Healthcare Inc (TSX: CLC, OTC: CMHIF). As I most recently wrote in the April 2011 Portfolio Update, I’ve been increasingly concerned in recent quarters about the company’s ability to manage its operations in the US. The sudden departure this week of Chief Executive Officer Paul Bristow and Chief Operating Officer Kent Nicholson is a tacit admission by the board of directors that nothing is getting better and a warning that earnings–due May 19–will reflect that. As of Thursday afternoon the stock is trading roughly where I recommended it initially in December 2008. Sell CML Healthcare.

Second, I’m cutting last month’s co-High Yield of the Month Colabor Group Inc (TSX: GCL, OTC: COLFF) from a buy to a hold. As I wrote then, the company is successfully taking advantage of rivals’ weakness to build scale with acquisitions. What I didn’t see coming was the apparent first-quarter deterioration in its ability to pass along fuel cost changes to customers. Management, in its quarterly conference call, claimed this would be temporary. But that’s too big a surprise to brush off. Colabor Group is a hold.

Finally, I’m cutting Yellow Media Inc (TSX: YLO, OTC: YLWPF) to a hold. First-quarter distribution coverage was solid, and the migration to the Internet continues. Meaningful debt maturities have also been pushed off to 2013. But my view is too many readers are taking positions that are too aggressive in this stock because of its high yield. Yellow Media is a hold.

As for the rest of the Portfolio, we’ll know a lot more as earnings results come in over the next month. Many picks continue to trade north of my buy targets, some well above. These shouldn’t be purchased except on pullback that takes them back below my targets. The following companies’ results and other developments are reviewed in the May Portfolio Update.