Zai Lab (NSDQ: ZLAB) raised $150 million in its US IPO after the company increased the size of the offering to 8 million shares from the originally proposed 5.8 million shares. Demand for the offering was strong, and Zai's stock is currently trading 50% above the IPO price at $27 per share. Zai is worth $1.4 billion at this price. If the underwriter places the 1.2 million share overallotment, the IPO will bring in $165 million.

The IPO priced at the top of its range, which was $16-$18. That shows the offering was well-received, but the real measure of the transaction's strength was the significantly larger number of shares offered: a 38% jump to 8 million shares before the underwriter's overallotment. It is a foregone conclusion that the 1.2 million shares of the underwriter's overallotment will be issued, raising to the total to 9.2 million shares, and the IPO will raise $165 million before fees.

The investor demand can be attributed in large part to the credibility of Zai's Dr. Samantha Du, the Chairman and CEO of the company, along with the team she has assembled. Dr. Du has been very visible in the rise of China novel drug development. Just four years old, Zai has moved rapidly forward, building the $1.4 billion company out of only $165 million in equity capital.

As we reported earlier, Zai used in-licensings to become a clinical-stage company in short order. It has six candidates so far, including a clinical-stage PARP inhibitor, already approved for Phase III China trials in ovarian and breast cancer. The company has completed Phase II proof-of-concept trials on the PARP inhibitor and a novel antibiotic.

In addition, Zai has moved beyond in-licensings. The company is building two manufacturing plants in Suzhou, one a small-molecule facility and the other a joint project with GE Healthcare for biologic drugs. It has started its own drug discovery operations, working with China academic institutions to discover novel drugs. And, Zai has filed to start a $150 million venture capital fund that will seek investing opportunities in young China life science companies. That VC fund is still raising capital, but it clearly will play to the strengths of Zai's team, with plenty of benefits available for Zai beyond the investments themselves.

Given Zai's record, it's no wonder the IPO went so well.

See our other stories on Zai Lab.

Disclosure: none.