Stock market today: S&P 500, Nasdaq slide as US-China tensions simmer; Dow steadies as big banks report

US stocks slumped on Tuesday after China upped the ante in its trade spat with the US, while investors digested the kickoff of third-quarter earnings season from Wall Street's banking giants. The Dow Jones Industrial Average (^DJI) dipped 0.1%, paring steeper earlier losses, while the S&P 500 (^GSPC) dropped 0.5%. The tech-heavy Nasdaq Composite (^IXIC) sank 1% to lead the retreat. The mood is unsettled after stocks' strong rebound on Monday, thanks to a fresh round of retaliation from Beijing to Presid ...