Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Theravance (UNKNOWN:THRX.DL), a developer of small-molecule drugs to treat respiratory diseases, bacterial infections, and central nervous system disorders, tumbled as much as 22% this morning. However, before you lunge for the sell button, consider that this was a planned drop as the company completed its spin-off of Theravance Biopharma (Nasdaq: TBPH) today.

So what: This move is no surprise, as Theravance had examined strategic alternatives last year and decided it was in the company's and shareholders' best interests to split into two separate entities. The Theravance that you see now will become a royalty management company that reaps the benefits of milestone and royalty payments associated with a handful of COPD assets tied to its collaboration with GlaxoSmithKline (NYSE:GSK). The partners currently have Anoro Ellipta and Breo Ellipta approved by the FDA for long-term COPD maintenance, with both drugs possessing blockbuster annual peak sales potential. This is the portion of the company that will be paying out $0.25/quarter in dividends moving forward.

On the other hand, Theravance Biopharma will be comprised of the company's remaining clinical-stage assets not tied to its Glaxo collaboration. This is the wild card of the group, since it pays no dividend and has no FDA-approved products.

Now what: If you were a shareholder as of the May 15 record date you now own shares in both companies, and I believe that balance of dividend payments from one and clinical pure-play from the other is worth hanging onto over the long run. However, looking at the two individual assets from the outside, Theravance's royalty management company is clearly the more attractive of the two, with a healthy dividend yield above 4% and, following its recent debt financing, ample cash on hand to fund this dividend for years. With the potential for more collaborative COPD assets to reach market, this would be the company out of the two that I'd suggest you follow the closest.