The S&P 500 fell to a two-month low Friday in a losing week for US stocks, with a profit warning from FedEx underscoring worries about economic weakness just as investors prepare for another interest rate increase by the Fed.

Triple witching is when markets are vulnerable to volatility spikes, and it happened on Friday.

The S&P 500 fell below 3,900 for the first time in over a month. The consumer staple and utilities groups were the only gainers. The major indexes all fell for the week, led by a decline in the tech-laden Nasdaq.

FedEx shares plummeted after the package delivery company issued a profit warning and scrapped its previous earnings guidance. The results were hurt by global volume softness. The CEO of FedEx predicted a recession for the global economy.

The US indexes opened at 9:30 a.m.

The Fed's rate hikes may cause the US economy to go into a recession. Bank of America's Michael Hartnett wrote in a weekly note that stocks have yet to see their lows of the year. The S&P 500 may be close to exiting its bear market.

The Fed-sensitive 2-year Treasury note flirts with 3.9%, suggesting that the Fed's aggressive campaign to kill off inflation is to be. The canary may still be alive, but is struggling to breathe.

The fed funds rate is expected to be raised by 75 basis points at the September meeting. Four times this year the Fed has raised rates.

There are other things happening today.

  • The argument that "there is no alternative" to buying stocks has been dashed as cash yields soar, said Bank of America. 
  • The German government seized three oil refineries in the country owned by Russian energy giant Rosneft to deal with the mounting European energy crisis. 
  • Turkey is set to sign a deal to use rubles to pay for 25% of its Russian natural gas imports, said Russian President Vladimir Putin.  
  • The boss of a "Black Swan" fund warned the Fed's rate hikes could cripple markets and the economy - and cause a bigger problem than inflation. 
  • The British pound sank to its lowest level against the US dollar in nearly four decades after an unexpected drop in retail sales stoked a fresh wave of UK recession fears. 
  • Fundstrat said it's time to buy the dip in stocks as data show inflation is falling and the market bottomed in June. 

Commodities and bonds are included.