(Adds U.S. market open, byline, dateline; previous LONDON)
* Oil majors drag down Dow; tech stocks boost Nasdaq
* BOJ eases, but still disappoints markets
* Oil faces big monthly loss on slowing economic growth
By Herbert Lash
NEW YORK, July 29 (Reuters) - Weak U.S. GDP data knocked down the dollar and yields on U.S. government debt on Friday, while Japanese government bond yields rose the most in eight years after investors coolly received the Bank of Japan's latest effort to boost the economy.
The U.S. economy grew far less than expected in the second quarter as inventory investment fell for the first time in nearly five years, though a surge in consumer spending suggested underlying strength and provided a silver lining for investors.
The BOJ doubled its purchases of exchange-traded funds, yielding to pressure from the government and financial markets for bolder action, but the move still disappointed investors who sought more audacious measures.
The yen jumped 2.39 percent against the dollar, whose decline put the trade-weighted dollar exchange rate on course for its biggest weekly fall in two months.
Japan's 10-year bond yield soared 10 basis points to -0.17 percent, on course for its biggest one-day rise since April 2008.
World equity markets were mostly higher.
A surge in Alphabet and Amazon.com lifted the Nasdaq following strong results after the bell on Thursday and helped the benchmark S&P 500 to rebound. But disappointing results from oil super-heavyweights Exxon Mobil and Chevron weighed on the Dow.
The Dow Jones industrial average fell 14.41 points, or 0.08 percent, to 18,441.94. The S&P 500 rose 3.42 points, or 0.16 percent, to 2,173.48 and the Nasdaq Composite added 12.20 points, or 0.24 percent, to 5,167.18.
Stocks in Japan absorbed the BOJ's decision a little more easily, in part because the central bank increased the purchases of exchange-traded funds (ETFs) in its easing package. Japan's Nikkei rose and European indices on better-than-expected results from Barclays and UBS, among others.
In Europe, the FTSEurofirst 300 index of pan-regional stocks closed a provisional 0.67 percent at 1,347.23.
Yields on the benchmark U.S. Treasury note pushed below 1.5 percent on the GDP data, with its price rising 10/32 and the yield falling to 1.4770 percent.
Gold hit a near three-week high on the U.S. GDP data, which is seen as keeping a Federal Reserve decision on when to raise interest rates on hold. U.S. gold rose 0.6 percent to $1,349.00 an ounce.
"The Fed's decision to lift rates is data dependent and if figures continue to disappoint, like second-quarter GDP growth today, gold will push higher," Commerzbank analyst Carsten Fritsch said.
Oil prices fell to their lowest levels since April, with Brent on track for its biggest monthly loss since December 2015, pressured by slowing economic growth that threatens to increase a supply overhang of crude and refined products.
Brent crude oil futures fell 40 cents to $42.30 per barrel. U.S. West Texas Intermediate (WTI) crude rose 15 cents to $41.29 a barrel. (Reporting by Herb Lash; Editing by Tom Heneghan and Nick Zieminski)