Chris Lao, Kapitall: Biotech company VIVUS just named another new CEO, so who stands to benefit from the change? The resignation of VIVUS(VVUS) CEO Anthony Zook (for medical reasons) after just a month on the job caught most investors off guard. This will be the third chief over a very short period of time. Shares tanked 13% on the week, and are now down over 20% over a monthly period. The executive shift could distract the company from delivering on better sales of obesity drug Qsymia. The change could also benefit the company’s competitors. [Read more from Kapitall: New PM Excites Market for Australian Raw Goods]Click on the interactive charts below to see data over time. What happened Zook took the CEO position after First Manhattan, an activist shareholder, won a proxy battle in the summer. He has been replaced by Seth Fischer, formerly an executive at Johnson & Johnson (JNJ). Over the last few months, Vivus failed to win coverage for Qxymia from insurance companies. Competitor Arena Pharmaceuticals (ARNA) also lacks insurance support for its obesity medication, Belviq. But as prescriptions grow steadily, future Belviq patients could win coverage from their insurers. Why Arena is more attractive Time will tell which drug – Qsymia or Belviq – will have higher demand. For now, Arena is more attractive because the firm has a strong distribution partner, Eisai. The partnership also means Arena shares its expenses. Conversely, Vivus does not have a partner, and its balance sheet is weakening. Vivus has $206 million in debt (as of the end of June 2013), and an upcoming FDA- mandated study would cost the company hundreds of millions. Vivus will need to boost sales to cover interest costs on debt and those associated with the new study. Shares in Arena are not faring very well. The stock is down on the year, but less so than Vivus. Over a three-month period, Arena shares are underperforming Vivus. This makes Arena a more attractive investment. Sales are steady but not explosive, but investors should remember that sales for a new drug will take months, not weeks, to grow faster. When that happens, Arena shareholders could be rewarded.