NEW YORK :Investors are growing uneasy that the rapid rise in public debt used to bankroll AI investments could strain the U.S. corporate bond market and eventually dampen the appeal of tech stocks, despite leverage across most major companies remaining low for now. Big tech firms are turning aggressively to the debt markets in their race to build AI-ready data centers, a shift for Silicon Valley firms that typically relied on cash to fund their investments. Since September, public bond