Fabrice Coffrini/AFP/Getty Images)
- US stock futures sank Wednesday as worries about Credit Suisse's financial health revived fears over banks.
- The Swiss bank's shares plunged 22% in Zurich after its top investor ruled out further support.
- Dow futures fell as much as 600 points premarket as the worries dented US investor sentiment.
US stocks looked set to fall at the opening bell Wednesday as a plunge in Swiss banking giant Credit Suisse's share price injected fresh unease into markets.