Klaviyo is trading 4.12% down now at $17.73, with the decline appearing to reflect continued post-earnings volatility and investor concern about margin pressure, valuation, and substantial insider selling. - No new company-specific announcement was identified for August 17, 2026. - Klaviyo raised revenue guidance but reduced its profit outlook. - Summit Partners sold 5 million shares on August 11; broader markets are mixed, leaving a macro explanation inconclusive.