By Hyunjoo Jin and Chris Prentice SAN FRANCISCO/NEW YORK (Reuters) -Did Elon Musk break U.S. securities laws again? Former securities officials and professors said Tesla Inc’s chief executive may have missed a key disclosure deadline and filed the wrong paperwork when he bought 9% of Twitter Inc, a platform regularly used by the outspoken billionaire. Securities and Exchange Commission regulators could use any shortfall to try to punish Musk more for other lapses, some believe. Musk on Monday disclosed that he bought a 9.2% stake in Twitter, making him the micro-blogging site’s largest shareho…