At last week's meeting, the commission argued that while the exact impact wasn't known, revenues from the tax were likely to offset the increased cost of government borrowing.

WSJ: EU Likely to Weaken Proposed Transaction Tax

Higher interest rates and a succession of credit rating downgrades have increased GMAC's cost of borrowing.

FORBES: GM's Profit Engine Faces Bumpy Road

The increased price of fixed-rate home loans since then has been driven by the increasing cost of borrowing the funds on the financial markets.

BBC: Fixed-rate mortgages rise again