BOSTON — The co-owner of a now-defunct foreign currency trading company has been sentenced to nine years in prison for defrauding investors out of more than $30 million.Craig Karlis of Hopkinton, Massachusetts, was also sentenced Tuesday in federal court in Boston to three years of probation and ordered to pay about $4.4 million in restitution to his victims and more than $450,000 to the Internal Revenue Service.Karlis pleaded guilty in March to multiple counts of wire fraud and tax-related crimes.