The U.S. economy is just "one shock" away from a double-dip recession, an economist says.

Economists at Bank of America's Merrill Lynch said Thursday the economy is "very fragile" and that odds of the U.S. entering another recession are placed at 35 percent.

"It would take a modest worsening in financial conditions, falling oil prices and rising unemployment. None of these are extreme scenarios," said Bank of America Merrill Lynch economist Michelle Meyer in a note to clients. "We argue that after a series of sucker punches earlier this year, the economy is only one shock away from falling into recession."

She notes, however, the recession, if it occurred, would likely be mild compared to the Great Recession the U.S. emerged from two years ago.

But even if America doesn't fall into a double-dip recession, conditions will "still feel like a recession to many."

"The economy has already been hit by a series of sucker punches earlier, this year including the jump in oil prices from the Middle East crisis, the collapse in auto production from the Japanese tsunami, and the confidence hit from the fiscal crisis in Europe and the U.S.," Meyer wrote.

Because the economy remains vulnerable because of key sectors that haven't recovered from the 2008 recession including family finances, housing and banking, just one more "shock" is all it would take to send the U.S. into a double-dip recession, Meyer said.