New York —  Tech stocks had a tumultuous week as concerns, including higher interest rates and mounting AI debt, continued to weigh on investor sentiment. The Nasdaq Composite fell 2.14% on Friday, bringing its weekly losses to roughly 4.5% — its worst week since June. The S&P 500 fell 1.09%, putting its weekly losses at almost 2%, also its worst week since June. The Nasdaq and S&P clinched record highs just 10 days ago. But since then, the market has stumbled as jitters spread about whether rising borrowing costs will put pressure on risky corners of the AI boom that are…