Shares in the wearable technology company Fitbit have soared more than 50 on their first day of trading in New York.br Initially priced at $20 a share, they jumped to $30.40 in early trading.br The company, which makes wristbands that track your calories and footsteps, raised $732million from the share sale.br Fitbit plans to use the money raised for research and development and possible acquisitions.