Banking regulators and lenders are coming under growing pressure to tighten up the methods used to originate so-called nontraditional home loans, the hottest corner of an otherwise cooling primary mortgage market. Whether tighter underwriting and better consumer disclosures will actually slow down the production of option ARMs, interest-only mortgages and minimalist documentation programs is a big unanswered question. Similar moves by regulators to raise standards in the subprime and home-equity markets in recent years...