The Financial Post reports in its Tuesday edition that marketing and data automation provider Klaviyo Inc. has attracted cornerstone investors including Blackrock for a U.S. initial public offering set to raise as much as $518-million (all figures U.S.). A Bloomberg dispatch to the Post says that the Boston company is offering 11.5 million shares for $25 to $27 each, while existing shareholders plan to sell 7.7 million shares, it said in a filing Sept. 11 with the Securities and Exchange Commission. It joins Instacart, which also set a price range and embarked on its IPO road show Sept. 11. Blackrock and Alliancebernstein LP have expressed interest in buying as much as $100-million of IPO shares, according to the filing. Based on its fully diluted share count, the company could be valued between $7.7-billion to $8.3-billion.