KEY POINTS
  • Guardant Health CEO Helmy Eltoukhy told CNBC on Thursday the company's liquid biopsy, Guardant360, is a "big game changer" when it comes to the detection of cancer.
  • The Silicon Valley oncology company, backed by SoftBank, sold 12.5 million shares at $19 in its initial public offering Thursday.
  • Less than an hour before close, the stock was trading at $34.37 per share.

Guardant Health shares popped almost 70 percent in their first day of trading on Thursday.

The Silicon Valley oncology company, backed by SoftBank, sold 12.5 million shares at $19 in its initial public offering. The stock was up more than 80 percent in mid-afternoon trading but later pared some of those gains, closing up 69.47 percent at $32.20 per share.