By Jaspreet SinghAug 5 (Reuters) - The New York Times added digital subscribers more slowly in the second quarter despite a busy news cycle that included the ‌U.S.-Israeli war with Iran and the FIFA World Cup, worrying investors who sent ‌its shares down more than 13%. The newspaper added about 280,000 digital-only subscribers in the second quarter, lower than an ​estimate of 295,300 from Visible Alpha and the 310,000 it added in the previous quarter. The slower second-quarter subscriber growth came even after it had dropped its paywall for all FIFA World Cup coverage on The Athletic and introduced new coverage formats, helping the sports website draw its "biggest audiences ever." The New York Times' flagship app features a TikTok-style vertical video feed in its Watch ​tab, complemented by a ‌Shows section that offers the company's longer-form, episodic video series for on-demand viewing. Total advertising ​revenue rose by 11.3% to $149.1 million, beating an estimate of $146.4 million.