ADARx Pharmaceuticals allocated approximately 55% of its $446.3 million initial public offering to 10 institutional investors after demand reached about 10 times the shares available, Bloomberg reported. The San Diego-based RNA-silencing drug developer sold 26.25 million shares at $17 each, above its original plan for roughly 21.9 million shares, and began trading on the Nasdaq Global Select Market under ADRX. The top 25 investors received roughly 95% of the offering, while about 100 investors received no allocation. AbbVie agreed to invest up to $100 million at the IPO price in a concurrent private placement that would give it an approximately 4.9% stake after both transactions close. Combined proceeds are expected to total about $535.2 million, excluding the underwriters' option to buy additional shares.