Recent steps by federal regulators make it clear: low down-payment loans, a feature of the housing market’s boom, are coming back.

On Monday, Federal Housing Finance Agency Director Mel Watt announced that mortgage-finance companies Fannie Mae and Freddie Mac would start backing loans with down payments as low as 3%.

And on Tuesday, three federal agencies approved a loosened set of mortgage-lending rules, removing a requirement for a 20% down payment for a class of high-quality loan known as a “qualified residential mortgage.”