A look at the day's business news:

Dow ends worst May in 70 years

Stocks cut losses but finished in the red Friday, ending a dismal month that saw the Dow Jones industrials suffer their worst May in 70 years, after a downgrade of Spain's debt reminded investors that Europe's economic woes continue.

The Dow Jones industrial average lost 122 points, or 1.2 percent, after having been down as much as 186 points earlier in the session. The S&P 500 index fell 14 points, or 1.2 percent, and the Nasdaq composite dropped 21 points, or 0.9 percent. 

Stocks were already weak before the ratings agency cut Spain's debt one
notch. While the cut still leaves the debt in investment grade territory, as
opposed to junk, it nonetheless managed to rattle investors in a thinly-traded session. 

Friday marked the end of a rough month on Wall Street in which stocks
plunged on worries about the European debt crisis, the weak euro and bets that the market advance had outpaced any economic recovery. 

Oil slips on Spain concerns 
 
Oil prices ended lower Friday after Fitch downgraded Spain's credit rating, renewing investors' fears that Europe's debt crisis could cut global demand for fuel.

Crude for July delivery fell 88 cents, or 0.8 percent, to $73.97 a barrel Friday. Gasoline prices fell for the 22nd consecutive day to $2.749 a gallon from $2.759 the day before, according to a survey by motorist group AAA.

Since the beginning of May, oil prices have fallen from $86.19 a barrel on fears that Europe's debt crisis will curb demand for fuel. Oil dipped to $68.01 a barrel on May 20 before bouncing back up to the mid-$70s this week.

Prices rose earlier as Europe fears took a back seat to political tensions between North and South Korea and President Obama's 6-month moratorium on permits to drill new deepwater wells, announced Thursday. Traders anticipated that Korea and the moratorium could lead to a decrease in world oil supply in the long term.

But when Fitch announced it had cut Spain's credit rating to a lower investment grade later in the day,  investors sold off higher risk assets such as stocks and oil.

Dollar mixed ahead of holiday 
 
The dollar was mixed against other currencies in thin and volatile trade Friday ahead of the U.S. holiday weekend.

The dollar rose 0.5 percent against the euro to $1.2301. The greenback was up 0.8% versus the British pound at $1.4459. It was down 0.3 percent against the Japanese yen at ¥90.80.

Europe was the big story in May, with its currency plunging 6% on concerns that a debt crisis would sweep through the Continent.

Treasurys edge higher as stocks fall 

Treasurys gained Friday, rebounding from the previous session's losses, as stocks slipped and investors prepared for a long holiday weekend.

The benchmark 10-year note rose 15/32 to 101-21/32, pushing the yield down to 3.31 percent, from 3.37 percent on Thursday. Bond prices and yields move in opposite directions.

The 30-year bond added 16/32 to 102-17/32 and yielded 4.23 percent. The 5-year note edged higher by 11/32 to 100, yielding 2.13 percent, while the 2-year note gained 5/32 to 99-29/32, yielding 0.81 percent.

Bonds were lifted as stocks dipped at the beginning of what is expected to be a quiet day of trading, ahead of a long Memorial Day weekend.

CNNMoney.com reporters Annalyn Censky, Blake Ellis, Julianne Pepitone and Alexandra Twin contributed to this report.