Abbott Laboratories is the latest pharma to hope that splitting up will unlock value. But last week's news that Abbott plans to become two companies - a diversified medical products company and a research-based pharmaceutical company - left key unanswered questions about the new pharma's future.

Nearly half of its revenues will come from one product - Humira adalimumab for autoimmune disorders - and it is unclear how long Abbott can sustain the robust sales growth trajectory of the anti-TNF antibody and whether its pipeline will be ready to kick in once Humira hits oral competition and patent expiry.