By Mike Dolan (Reuters) -What matters in U.S. and global markets today By Mike Dolan, Editor-At-Large, Finance and Markets Wall Street's 'fear gauge' of implied stock market volatility touched its highest in almost four months on Tuesday as a fresh wave of AI excitement jostled with trade war tensions and the onset of the third quarter earnings season. The VIX earlier hit its highest since mid-June as U.S.-China trade exchanges turned sour again overnight following Monday's Broadcom-led stock rebound. ...