NEW YORK — Home buyers and homeowners who have bad credit or live in high-cost cities are having a hard time getting new mortgages because investors on Wall Street are still skittish, according to data released this week. And mortgage brokers say the government's new efforts to loosen lending restrictions are providing little relief so far.

The mortgage bond market has virtually evaporated for new loans that don't meet the more prudent guidelines of government-backed mortgage giants like Fannie Mae or Freddie Mac. The share of these so-called "non-agency" mortgage bonds plunged to 6 percent of the market in the first quarter, the lowest share in almost two decades, and down from 51 percent in the first quarter last year, according to trade publication Inside Mortgage Finance.

That hurts borrowers with subprime credit, for example, entrepreneurs or people without steady paychecks, or people who needed loans larger than government limits. While Congress last month raised the limits on loans that can be sold to government agencies to $729,750, borrowers are still being shut out.

There are new restrictions on these loans "that makes them pretty useless," said Ginny Ferguson, of Heritage Valley Mortgage in Pleasanton, Calif.

The restrictions prevent homeowners from refinancing if they take out more than 5 percent of their equity, or from consolidating two mortgages into one. Also, buyers in areas where prices are falling, like California and Florida, must pony up larger down payments.

Some lenders haven't even started processing the new conforming loans. Until June 1, when Fannie Mae and Freddie Mac roll out an updated underwriting system, lenders must manually underwrite these mortgages, Ferguson said.