NEW YORK - US stocks ended in the red on Friday, falling to two-month lows as a warning of impending global slowdown from FedEx hastened investors' flight to safety at the conclusion of a tumultuous week.

All three major US stock indexes slid to levels not touched since mid-July, with the S&P 500 closing below 3,900, a closely watched support level.

Staggering past the finish line of a week rattled by inflation concerns, looming interest rate hikes and ominous economic warning signs, the S&P 500 and the Nasdaq suffered their worst weekly percentage plunges since June.

"It's been a tough week. It feels like Halloween came early," said David Carter, managing director at JPMorgan in New York.

"We are facing in this toxic brew of high inflation, high interest rates and low growth, which isn't good for stock or bond markets."

Risk-off sentiment went from simmer to boil in the wake of FedEx Corp's withdrawal of its earnings forecast late on Thursday, citing signs of dampening global demand.

FedEx's move followed remarks from the World Bank and the IMF, both of which warned of an impending worldwide economic slowdown.

A deluge of mixed economic data, dominated by a hotter-than-expected inflation report (CPI), cemented an interest rate hike of at least 75 basis points at the conclusion of the Fed's monetary policy meeting next week.

"While the market is expecting a big bump in the Fed's rates next week, there is tremendous uncertainty and concern about future rate increases," Carter added.

"The Fed is doing what it needs to do. And after some pain, markets and the economy will heal themselves."

Financial markets have priced in a 18 per cent likelihood of a super-sized, 100 basis point increase to the Fed funds target rate on Wednesday, according to CME's FedWatch tool..

The Dow Jones Industrial Average fell 139.4 points, or 0.45 per cent, to 30,822.42, the S&P 500 lost 28.02 points, or 0.72 per cent, to 3,873.33 and the Nasdaq Composite dropped 103.95 points, or 0.9 per cent, to 11,448.40.

Nine of the 11 major sectors of the S&P 500 ended in negative territory, with energy and industrials suffering the sharpest percentage drops.

Dow Transports, viewed as a barometer of economic health, plummeted 5.1 per cent.

That drop was led by FedEx shares tanking by 21.4 per cent, the biggest drop in the S&P 500.

Peers United Parcel Service and XPO Logistics slid 4.5 per cent and 4.7 per cent, respectively, while Amazon.com slipped 2.1 per cent.

The session also marked the monthly options expiry, which occurs on the third Friday of every month. Options-hedging activity has amplified market moves this year, contributing to heightened volatility.

The CBOE Market Volatility index, often called "the fear index," touched a two-month high, breezing past a level associated with heightened investor anxiety.

Declining issues outnumbered advancing ones on the NYSE by a 3.04-to-1 ratio; on Nasdaq, a 2.24-to-1 ratio favoured decliners.

The S&P 500 posted no new 52-week highs and 56 new lows; the Nasdaq Composite recorded 21 new highs and 387 new lows.

Volume on US exchanges was 16.92 billion shares, compared with the 10.72 billion average for the full session over the last 20 trading days. REUTERS