The talks also focused on "China's pledge to purchase a substantial amount of agricultural, energy, manufactured goods, and other products and services from the US" according to the USTR.
Gold prices rose on Wednesday, with spot gold (XAU=) up 0.68 percent to $1,293.65 per ounce.
The trade war has seen both sides impose tariffs on hundreds of billions of dollars worth of goods from each other.
Speaking at a daily news briefing in Beijing, Chinese foreign ministry spokesman Lu Kang confirmed both sides had agreed to extend the talks beyond Monday and Tuesday as originally scheduled.
Beijing has tried to defuse pressure from its trading partners for more sweeping changes by offering concessions on investment regulations and stepping up purchases of American soybeans, natural gas and other exports. The gains for USA indexes faded slightly after President Donald Trump and Democratic leaders said Trump cut short a meeting on ending the partial shutdown of the federal government.
Australia will consider asylum bid of Saudi woman who fled to Thailand
Alqunun's father - a senior Saudi official - and her brother, who she says often physically abused her, are now in Thailand . Thai officials had tried to force her take a flight to Kuwait, Saudi Arabia scheduled for the morning of January 7.
Yesterday, the US Trade Representative's offices said in a statement officials from the two sides discussed "ways to achieve fairness, reciprocity and balance in trade relations". It's a tight window in which to nail down deep changes to China's economic model, some of which past US administrations advocated for years and USA lawmakers on both sides of the aisle support.
"At the beginning of 2018 the global economy was firing on all cylinders, but it lost speed during the year and the ride could get even bumpier in the year ahead, " World Bank Chief Executive Officer, Kristalina Georgieva, said in a semi-annual report released late on Tuesday.
Shanghai economist Andy Xie says the talks wouldn't have been extended if they were going poorly.
While Beijing could take "easy steps" like importing soybeans, cotton and liquefied natural gas from the USA, there would be greater difficulties on the technology front, including China proving its commitment to intellectual property rights with penalties on violators and addressing U.S. restrictions on China's electronic components, Pang said. US negotiators are also taking steps to ensure the Chinese government actually follows through on its promises. Trump has said he would increase those duties to 25 per cent from 10 per cent now if no deal is reached by March 2, and has threatened to tax all imports from China if Beijing fails to cede to U.S. demands.
USA companies also want action on Chinese policies they complain improperly favor local companies.
The U.S. economy grew at an annual rate of 3.4 per cent in the third quarter and unemployment is at a five-decade low.
State Department Warns Americans About Traveling to China
December 14: Canadian officials are granted consular access to Kovrig, and McCallum meets with him in Beijing. The Chinese government has not drawn a direct link between the detention of any Canadian and Meng's arrest.
Analysts said the positive momentum from the working talks will need to be followed up by more senior officials, such as Liu and USA trade representative Robert Lighthizer, who is in charge of overall negotiations on the United States side.
The standoff also reflects American anxiety about China's rise as a potential competitor in telecommunications and other technology.
But it also said any deal with China must be followed up with ongoing verification and enforcement.
With cooling economic growth raising the urgency for a settlement, this week's talks went ahead despite tension over the arrest of a Chinese tech executive in Canada on USA charges related to possible violations of trade sanctions against Iran.
Official US fuel storage data from the Energy Information Administration is due at 1800 GMT on Wednesday.
Huawei punishes employees for tweeting New Year greetings using iPhone
Huawei deleted its original New Year's message and reposted it, this time with the source displaying "Twitter Media Studio". The team eventually deleted the tweet and sent a new one from a masked Twitter client almost four hours later.