SAN FRANCISCO — The rush of so-called unicorn start-ups toward the public markets had a rocky start. But Thursday indicated that investors remain eager to get a piece of them.

Shares in Pinterest, the digital pin board, jumped over 28 percent on its first day of trading as a public company. The company’s stock began trading at $23.75, above the initial public offering price of $19, and finished the day at $24.40.

The company’s fully diluted market capitalization totaled over $16 billion, making it more valuable than Macy’s or Nordstrom, the retail chains. More important to investors, the price put the company’s value above its last private valuation of $12 billion, avoiding a disappointing outcome.

Zoom, a videoconferencing company, also went public to tremendous investor demand on Thursday. Shares in the company, which was last valued by private investors at $1 billion — the threshold for unicorn status among private start-ups — skyrocketed 80 percent in early trading. The shares ended the day up more than 72 percent, closing at $62. The company’s fully diluted market capitalization now exceeds $18 billion.