While most Americans have two parts to their investment portfolio -- their homes and their stocks -- they are knitted together in critical ways. Which is why the current stock market plunge may already be hurting consumer confidence when it comes to the housing market, according to some experts. The big sell-off in stocks that began last week has already sent mortgage rates plummeting, but so far that's only translated into bigger demand for refinancings. The bigger questions for housing markets are whether stock market volatility will undermine homebuyer confidence, and whether declines in equity prices will mean buyers will have a harder time scraping together down payments. “The biggest impact will be on consumer confidence,” said Pat Stone of Williston Financial. “Th...