Poison or Placebo? Evidence on the Deterrent and Wealth Effects of Modern Antitakeover Measures

This paper provides large-sample evidence that poison pill rights issues, control share statutes, and business combination statutes do not deter takeovers and are unlikely to have caused the demise of the 1980s market for corporate control, even though 87% of all exchange-listed firms are now covered by one or another of these antitakeover measures. We show that poison pills and control share statutes are reliably associated with higher takeover premiums for selling shareholders, both unconditionally and conditional on a successful takeover, and we provide updated event-study evidence for the three-quarters of all poison pills not yet analyzed.

Consensus recommendations for hyperpolarized [1‐ 13 C ]pyruvate MRI multi‐center human studies

MRI of hyperpolarized (HP) [1‐13C]pyruvate allows in vivo assessment of metabolism and has translated into human studies across diseases at 15 centers worldwide. To determine consensus on best practice for multi‐center studies for development of clinical applications. This paper presents the results of a two‐round formal consensus building exercise carried out by experts with HP [1‐13C]pyruvate human study experience. Twenty‐nine participants from 13 sites brought together expertise in pharmacy methods, MR physics, translational imaging, and data analysis with the goal of providing recommendations and best practice statements on conduct of multi‐center human studies of HP [1‐13C]pyruvate MRI. Overall, the group reached consensus on approximately two‐thirds of 246 statements in the questionnaire, covering HP 13C‐pyruvate preparation; MRI system setup, calibration, and phantoms; acquisition and reconstruction; and data analysis and quantification. Consensus was present across categories. Examples include: (i) Different HP pyruvate preparation methods could be used in human studies, but the same release criteria have to be followed; (ii) site qualification and quality assurance must be performed with phantoms and the same field strength must be used, but the rest of the system setup and calibration methods could be determined by individual sites; (iii) the same pulse sequence and reconstruction methods were preferable, but the exact choice should be governed by the anatomical target; (iv) normalized metabolite area‐under‐curve values and metabolite area under curve were the preferred metabolism metrics. The consensus proces revealed that HP[1‐13C] pyruvate MRI as a technology has progressed sufficiently to plan multi‐center studies. The work confirmed areas of consensus for multi‐center study conduct and identified where further research is required to ascertain best practice