Bitcoin has broken above US$80,000 for the first time in three months, riding a broader rally in alternative assets triggered by Washington’s efforts to tame US bond yields.The world’s largest cryptocurrency traded above US$80,900 on Tuesday, jumping roughly 25 per cent over the past week and signalling an early recovery from a prolonged market slump.While bitcoin remains nearly 36 per cent below its record high of US$126,000 set in October, the sharp rebound has prompted observers to predict the end to this year’s crypto downturn that has seen the original crypto token shed nearly half of its value.Bitcoin’s price hike this week shows characteristics of an early bull market, according to Allen Ding, director of Hong Kong-based Bitfire Research, a unit of Bitfire Group, a Hong Kong-listed crypto asset management firm previously linked to the Chinese crypto exchange Huobi, now known as HTX.The sharp crypto rebound came after the US Treasury announced plans last week to ramp up the buy-backs of long-term US debts in an attempt to lower surging bond yields and boost the economy, pushing up broader investor appetite for hard or alternative riskier assets to hedge against the US dollar.What is Polymarket, the gambling site that lets you bet on almost everything?Gold also traded at a three-month high of US$4,698 an ounce on Tuesday, extending a 5.1 per cent gain last week.