The down payments required by banks to buy homes have "ballooned since the housing bust, forcing many people to rethink what they can afford and potentially shrinking the pool of eligible buyers," according to a front-page article in today's edition of The Wall Street Journal by S. Mitra Kalita.

The median down payment in nine major American cities rose to 22 percent in 2010 on properties bought through conventional mortgages, the article said, adding that "that percentage doubled in three years and represents the highest median down payment since the data was first tracked in 1997."

Banks have found that "larger down payments discourage delinquencies by increasing the buyer' exposure to loss and reducing the impact of declining prices, the article said, adding that "many home buyers placed little, if anything, down during the boom."

The article said that Peter Norden, chief executive officer of Real Estate Mortgage Network Inc., of Edison, New Jersey, said that "if there is a scenario where the government talks about raising down payments to 20 percent on conventional loans, you would absolutely crash the housing market."

The article said that the median down payment hovered around 20 percent in the late1990s and began to creep downward in 2001 in the nine cities Zillow analyzed: Chicago, Phoenix, Las Vegas, and Miami-Fort Lauderdale and Tampa in Florida, and San Francisco, Los Angeles, San Diego and Stockton in California.

"It fell as low as 4 percent in the fourth quarter of 2006, and in some markets came close to zero," the article continued, adding that "as home prices rose at faster rates than American's incomes in recent decades, banks began to accept lower down payments to create greater affordability and spur home-buying."