Klaviyo is trading at $19.51, up 11.36% in pre-market, with no verified explanation for the sharp rise. - Klaviyo’s newsroom lists an October 19 announcement naming it an official partner of the Atlassian Williams F1 Team, but available information does not establish that it caused the move. - Broader market sentiment is mixed; the supplied Nasdaq indication is lower and does not clearly explain the rise.