Cummins Inc. shares fell 14% -- its biggest decline in four years -- after Standard & Poor's cut its debt ratings for the largest maker of heavy-duty diesel engines to junk status.

Shares fell $3.60 to $21.98 at 4:15 p.m. Wednesday in New York Stock Exchange composite trading, according to Bloomberg News. The percentage decline was the largest since September 1998. The stock has declined 43% this year.
S&P cited slowing sales growth for power generators and truck engines in lowering ratings on Cummins to BB+ from BBB- on Tuesday.
The move affected about $925 million in debt securities. The ratings company also removed Cummins from review and said the company's outlook was negative.
"Given the economic situation, the change of rating isn't unexpected," Cummins spokesman Jason Rawlings said. The company doesn't expect the downgrade to hurt its ability to finance its operations, he said. The ratings change won't affect any of the company's loan agreements, Rawlings said.