The country's two largest lenders - BBVA and Santander - were among the ten financial institutions to see their levels cut by Standard & Poor's (S&P's), while Fitch revealed it is reducing the position of six banks.
According to the two ratings groups, a bleak outlook for Spain's economic future was the reason for such movement.
S&P noted: "Spain's economy faces dimming growth prospects in the near term, real estate market activity remains depressed and turbulence in the capital markets has heightened."
Regarding the nation's two major banks, S&P's cut the rating of Santander by one notch to AA-, while that of BBVA - which has been in operation for more than 150 years - was downgraded one level to A+.
It claimed lenders in the country would continue to be affected by the worsening Spanish economy for at least the next 15 to 18 months.
By Claire Archer