TOKYO—In a sign of how Amazon.com Inc. is reshaping online shopping globally, Yahoo Japan shares plummeted Thursday after it warned of a big increase in marketing costs as it struggles to compete with the Seattle juggernaut. Yahoo Japan, a joint venture between SoftBank Corp. and Yahoo Inc., is the country’s biggest search portal but has been squeezed in e-commerce as Amazon benefits from years of aggressive investment in Japan,...

Source: Wall Street Journal April 27, 2017 12:16 UTC