The banks, when they initially went into leasing, were paying relatively high tax rates. However, since municipal bonds are tax-exempt, their heavy investments in municipals lowered the banks' effective tax rates. Similarly, when the REIT loans began to sour, this further reduced the bank's income, and consequently cut the effective tax rate even further. Since the lease investments were predicated on obtaining tax shelters, and since the value of these tax shelters is dependent on the banks' tax rates, when the effective tax rates were lowered, this reduced the value of the tax shelters and consequently reduced the profitability of the lease investments.