GameStop said it would swap $1.4 billion worth of debt for stock on Monday, sending the videogame retailer’s shares tumbling. The one-time meme stock sank 13% to $18.92 on Monday, wiping out all of its gains for the year and heading for its worst daily percentage decline in more than a year, according to Dow Jones Market Data. The was 1.4% higher after President Donald Trump said the U.S. would restart talks with Iran.