SINGAPORE (Reuters) - Bitcoin was perched at a two-year peak on Tuesday, breaking above $68,600 and stalking the all-time high as money keeps rushing into the largest cryptocurrency by market value.

Bitcoin has gained 50% this year and most of the rise has come in the last few weeks when inflows into U.S.-listed bitcoin funds have surged.

On Tuesday, it was at $68,500 in Asian hours, having reached a session high of $68,828, a whisker away from the all-time peak of $68,999.99 it set in November 2021.

Spot bitcoin exchange-traded funds were approved in the United States earlier this year. Their launch opened the way for new large investors and has re-ignited enthusiasm and momentum reminiscent of the run up to record levels in 2021.

"It's crypto mania 4.0, and I think if we continue to see fairly low bond and rate volatility, it could keep going. There's definitely something of an irrational behaviour creeping into the market," said Kyle Rodda, senior markets analyst at Capital.com.

Net flows into the 10 largest U.S. spot bitcoin funds reached $2.17 billion in the week to March 1, with more than half of that going into BlackRock's iShares Bitcoin Trust, according to LSEG data.

"The appetite to gain exposure to Bitcoin is reaching insatiable levels," said Tony Sycamore, a market analyst at IG.

"While Bitcoin overbought in the short term, the move is far from done, and dips will be well supported with a move towards $80,000 not out of the question."

The rally has come in tandem with records tumbling on stock indexes from Japan's Nikkei to the S&P 500 and tech-heavy Nasdaq and with volatility gauges in equities and foreign exchange turning lower.

Smaller rival ether has hitched a ride on speculation that it too may soon have exchange-traded funds driving inflows and is up over 50% for the year and was last at $3,649.

A regulatory filing on Monday showed that U.S. Securities and Exchange Commission has further delayed its decision on an application by asset manager BlackRock for its spot ethereum exchange-traded fund.

Elsewhere, the number of dollar-pegged stablecoins issued by Tether has crossed $100 billion, the crypto company said on its website on Monday. Tether issues a stablecoin which is designed to maintain a constant value of $1.

(Reporting by Ankur Banerjee in Singapore)