Shares of Blue Buffalo surged 35% above their initial price on the first day of trading, raising $677 million in its initial public offering.

Blue Buffalo, listed on the Nasdaq Stock Market under the symbol BUFF, gained 36% to $27.20 at the close. At that level, the company is being valued at $5.3 billion.

Existing shareholders sold 33.8 million shares for $20 per share. They initially offered 29.5 million for $16-$18 each.

Blue Buffalo says it will issue up to 35,934 shares to about 1,700 non-management employees at no cost to them.

Blue Buffalo’s IPO was the year’s fifth largest. The only other consumer-facing company that had a bigger IPO was Fitbit, which makes wearable fitness trackers.

When it announced its filing for an IPO, analysts estimated the company could raise to up $500 million.