There's no getting around it: This morning's jobs report was bad. Economists surveyed by Thompson Reuters were expecting total payrolls to grow last month by 200,000. Analysts and traders were accordingly shocked when the Department of Labor announced that the actual figure was only 88,000. An investment strategist quoted by Bloomberg News summed it up succinctly: "This report is a huge disappointment."

Few companies are being hit harder by the news than insurance companies. For the past few months, there's been a growing chorus of speculation that the Federal Reserve will wean the economy off its current, highly accommodative monetary policy -- the central bank is purchasing $85 billion in Treasuries and agency mortgage-backed securities a month. That would mean higher interest rates and thus larger profits for insurers.

The likelihood that this will happen now seems to have evaporated -- if it was ever likely at all, considering the Fed's previous statement that it will keep rates low into 2015. "Fed officials have been wary of pulling back too quickly, given the disappointments the economy has produced in the past during this recovery," said The Wall Street Journal's Jon Hilsenrath. "[Today's] report reinforces that wariness."

What this means for insurance companies like MetLife (NYSE:MET) is a prolonged period of low interest rates, making it difficult for them to turn a profit without taking on too much risk. As an analyst quoted by Bloomberg News put it in a research note to clients, "Sustained low interest rates present a challenge for life insurers because of reduced reinvestment rates."

It's for this reason that six of the S&P 500's 20 worst-performing stocks today are insurance companies. AFLAC (NYSE:AFL) is leading the way down, having lost 4.1%, followed by Prudential Financial (NYSE:PRU), Unum Group (NYSE:UNM), Hartford Financial, and Lincoln Financial. For its part, MetLife has lost 2.7% of its value today.