* U.S. Treasuries nearly flat
* Wall Street off as retail earnings disappoint
* Investors warily eye Thailand martial law declaration (Updates prices, adds oil closing prices)
NEW YORK, May 20 (Reuters) - Global stock indexes declined on Tuesday after weaker-than-expected earnings, while the dollar fell for a fifth straight session against the yen.
Retailers such as TJX Companies, which posted lower-than-expected quarterly revenue, were among the biggest drags on U.S. stocks, along with Caterpillar, which said retail statistics for the three months to April were down 13 percent.
A persistent fall in U.S. Treasury yields, reflecting uncertainty about global economic growth, has undermined the dollar. But U.S. Treasuries were mostly flat.
"There's a little bit of risk-off sentiment given the declines in stocks," said Kim Rupert, managing director for fixed income at Action Economics in San Francisco.
Concerns surrounding Ukraine remained an "undercurrent," she said.
MSCI's all-world equity index, which tracks shares in 45 nations, was down 0.4 percent, while European shares closed down 0.1 percent.
Vodafone shares fell after the company wrote down the value of some of its European businesses, citing fierce competition and regulatory changes.
On Wall Street, shares extended declines in late trading. The Dow Jones industrial average fell 112.64 points or 0.68 percent, to 16,399.22, the S&P 500 lost 9.51 points or 0.5 percent, to 1,875.57 and the Nasdaq Composite dropped 22.52 points or 0.55 percent, to 4,103.29.
Shares of TJX tumbled 7.1 percent to $54.25 while the S&P retail index lost 0.8 percent.
Investors will soon turn their focus to see whether minutes from the last Federal Reserve policy meeting, due on Wednesday, will shed light on the likelihood and timing of rate rises.
At the same time, markets are optimistic over support from the European Central Bank, one of the few central banks still keeping monetary policy loose.
The dollar was down 0.2 percent against the yen to 101.30 yen. The pair traded below the 200-day moving average, a key technical gauge, for a second straight day.
The Australian dollar was the biggest mover of the day, falling to a two-week low against the greenback on a slide in prices for iron ore, the country's biggest export earner.
Benchmark 10-year U.S. Treasury note prices were up 6/32 to yield 2.512 percent, from 2.536 percent late Monday.
Brent crude rose 32 cents to settle at $109.69 a barrel, supported by instability in Libya, while U.S. crude futures slipped 17 cents to settle at $102.44. Platinum edged higher as South Africa's longest and costliest miners' strike continued. Spot platinum was up 0.4 percent.
Nervousness also washed in from Asia, where Thailand declared martial law after months of unrest.
MSCI's broadest index of Asia-Pacific shares outside Japan slipped 0.4 percent. (Additional reporting by Marc Jones and John Geddie in London and Sam Forgione and Chuck Mikolajczak in New York; Editing by Dan Grebler and James Dalgleish)