* Yuan sees biggest drop in almost three years after PBOC moves
* World stocks at 6-year high after Wall St hits all-time peak
* Gold holds recent gains, major currencies rangebound
By Marc Jones
LONDON, Feb 25 (Reuters) - World shares hit a six-year peak on Tuesday on the heels of a record Wall Street high, while moves by China to stamp out easy betting on the yuan triggered the currency's biggest drop in over three years.
The upbeat mood among equity investors in the United States and Europe helped steady markets after the sharp plunge in the yuan and talk of credit tightening led Beijing stocks to their biggest drop since September.
The yuan has entered a dramatic weakening cycle in recent weeks, guided by a series of moves by the central bank aimed at instilling caution into those who for years have been betting on its rise versus other major currencies.
Tuesday saw a significant acceleration in the move. The yuan's sharpest drop since November 2010 extended its fall in the past week to just over 1 percent, amid talk the People's Bank of China (PBOC) had been discreetly intervening in the spot market.
"The yuan move has some relation to the slowdown in the Chinese economy but it looks more that it has been orchestrated by the PBOC to make it more of a two-way street for speculators," said Societe Generale strategist Alvin Tan.
"It is likely to simmer down from here, it has wiped out pretty much all of the speculators' recent gains now."
China allows the yuan to move 1 percent above or below a midpoint set daily but experts believe the recent depreciation is intended to set the stage for a widening of that band to 2 percent or more this year to make it more free moving.
Uncertainty over China is stoking worries about a faster-than-projected slowdown in its massive economy and is combining with worries about other key emerging markets like Ukraine, Thailand, Nigeria and Turkey where there has been unrest.
It also comes as the U.S. Federal Reserve starts to scale back its huge stimulus - a potent mix that has made investors nervy and has seen $38 billion pulled out of emerging markets over the last 17 weeks.
CRUISING AT ALTITUDE
MSCI's all world index, which tracks stocks in 45 countries, was in positive territory for the 13th session in 15 as it sat at a six-year high, although with Wall Street expected to open lower later it was likely to lose ground.
In Europe, the urge to take profits after seven straight sessions of gains was too strong and the pan-regional FTSEurofirst 300 sagged 0.4 percent, led by a 1 percent drop from London's FTSE.
The euro and benchmark German government bonds kept to tight recent ranges.
Investors were also focused on new European Commission economic forecasts for the 28 EU member states, covering GDP, inflation, unemployment and debt.
The EU's executive slightly increased its growth estimate for the euro zone to 1.2 percent in 2014, with a further 1.8 percent expansion next year. It foresaw euro zone inflation of 1 percent this year and 1.3 percent in 2015, still well short of the European Central Bank's target of just below 2 percent.
A detailed breakdown on Tuesday of Germany's fourth quarter GDP data confirmed quarterly growth of 0.4 percent with exports leading the way. Foreign trade, which had been weak for much of 2013, added 1.1 percentage points to GDP in the fourth quarter, but there was an alarm bell from weak domestic demand which subtracted 0.7 percentage points from growth.
The revisions to the Commission's forecasts add to the information the ECB has says it needs before deciding whether to take any policy action at its March meeting next week.
Goldman Sachs pushed back its prediction of a rate cut until April on Tuesday, although it didn't rule out a move by the ECB to keep money market liquidity topped up by ending its weekly 'sterilisation' of past government bond purchases.
"It will be a big step for the ECB but a small step for mankind," said Neil Williams, chief economist at fund manager Hermes.
WALL STREET HIGH
Away from China, Japan's Nikkei bolted ahead by 1.4 percent to breach the 15,000 barrier, which in turn gave the dollar a slight lift on the yen, although it later sagged.
It had followed in the footsteps of Wall Street, where the benchmark S&P 500 hit an intra-day record as the Nasdaq punched to peaks last seen almost 14 years ago.
Another data deluge is due including confidence readings, housing market surveys and retail sales figures, while stocks are likely to remain on alert after Monday's fresh flurry of merger and acquisition activity.
U.S. Treasuries prices, which provide the benchmark for global borrowing costs, were steady after a dip overnight, with yields on the benchmark 10-year note holding just below 2.74 percent in early U.S. trade.
The swinging risk sentiment continued to buffet emerging markets. The latest twist in a government corruption scandal in Turkey saw the lira hit two-week lows versus the dollar and stocks fell 3 percent.
Ukraine fared better, with its sovereign dollar bonds keeping most of Monday's stellar gains as hopes grew it would receive Western aid to prevent a debt default after the ouster of president Viktor Yanukovich.
Gold which has benefited from recent global uncertainty, was also firm at around $1,333 an ounce after touching a four-month high. It faces stiff resistance at October's peak of $1,361.60.
Oil prices faded just a little after supply worries gave them a boost the session before. Brent crude dipped 34 cents to $110.30 a barrel, while U.S. oil fell 97 cents to $101.24 a barrel.