The credit ratings of five regional US banks have been lowered by S&P Global Ratings, as the agency warned of the challenges facing the sector in the wake of the Silicon Valley Bank collapse earlier this year.

S&P downgraded KeyCorp, Comerica Inc., Valley National Bancorp, UMB Financial Corp. and Associated Banc-Corp by one notch each on Monday, citing their exposure to the “tough” lending environment and the pressure on their deposit bases.

The agency also said it had negative outlooks for several other regional banks, indicating that further downgrades could be possible in the future. None of the banks S&P rates have positive outlooks, reflecting the bleak prospects for the industry.

The ratings actions follow a similar move by Moody’s two weeks ago, which also downgraded some regional banks and put others under review. Moody’s also raised concerns about the credit ratings of some larger banks, such as Bank of New York Mellon, State Street and Northern Trust.

The regional banking sector has been hit hard by the fallout from the collapse of Silicon Valley Bank, which was one of the largest lenders to technology startups and venture capitalists. The bank failed in February after suffering massive losses from its exposure to fraudulent loans and investments.

The bank’s failure triggered a wave of deposit withdrawals from other regional banks, as customers feared for their safety and sought higher interest rates elsewhere. Many regional banks have had to raise their deposit rates to retain customers, which has eroded their profitability and capital ratios.

S&P highlighted the decline in deposits as one of the main reasons for its downgrades. For example, it noted that Comerica’s average deposits fell by $14 billion from the second quarter of last year to this year. It also pointed to its “relatively high proportion of commercial and uninsured deposits,” which are more prone to outflows.

The agency also said that the regional banks faced challenges in growing their loan portfolios, as demand for credit remained weak and competition intensified. It said that the banks’ loan quality could deteriorate if the economic recovery slowed down or reversed.

S&P said it would continue to monitor the performance and outlook of the regional banks, and adjust its ratings accordingly. It said it could lower its ratings further if the banks’ earnings, capital or liquidity deteriorated significantly, or if they faced regulatory actions or litigation risks.