Technology tycoons lost $15.5 billion from their fortunes on Monday as a sell-off of the sector’s most valuable corporations intensified. Facebook Inc.’s Mark Zuckerberg watched the biggest drop in net worth of $3.2 billion, followed by a $1.3 billion deterioration for Alibaba Group Holding Ltd.’s Jack Maand a $1.2 billion wipeout for Amazon.com Inc.’s Jeff Bezos. The 59 tech mogul on the Bloomberg Billionaires Index control $942 billion, more than any other industry in the ranking.