By Zaheer Kachwala and Joel Jose Dec 12 (Reuters) - Broadcom shares fell more than 11% on Friday after the chipmaker warned growing sales of lower-margin custom AI ​processors were squeezing profitability, sparking worries that the business may be less ‌lucrative. The warning on margin impact deepened investor jitters over Big Tech's AI returns, a day after Oracle fell ‌10.8% due to high capital spending for a debt-funded AI infrastructure buildout. Investor scrutiny of AI spending has intensified in r ...