The Trans-Pacific Partnership (TPP), which would encompass 40 percent of the global economy and include 12 nations, has been the subject of negotiations for years.
US President Barack Obama said in June he hoped to have an agreement on framing the deal, which has been slowed by debate on key details between the US and Japan, by November.
Australian Trade Minister Andrew Robb, hosting the Sydney talks, told the opening plenary that reports from negotiators were that "there does seem to be a real head of steam".
"I think a lot of progress has been made," he said.
"Clearly I think we are working now to try and conclude this agreement by the end of this year."
Robb admitted trade ministers had a "very big programme" during the three-day talks which attracted a small group protesting against the "secret deal".
"I do think this agreement is starting to take some real shape," Robb said.
"We are at a point where we are trying to make as many final decisions as we can and bring this thing to completion."
US Trade Representative Mike Froman said since the last TPP meeting in Singapore in May, trade ministers had been in "almost constant" negotiations.
"Going into this weekend we are enjoying a great deal of momentum and focus across the board, and it's up to us to seize that momentum and make sure that this meeting is maximally productive," he said.
The negotiations have been slowed while the United States and Tokyo debate key details, including Japanese tariffs on agricultural imports and US access to Japan's auto market.
"The issues left at the end are often times the most challenging but now is the time to start working through those and finding solutions," Froman said.
"We've got some work to do and the table is set in a way that will allow us to make progress on these difficult remaining issues."
The 12 prospective TPP members are Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the United States and Vietnam.
Concerns about impact on cost of medicine
A small group of protesters gathered outside the TPP meeting at Sheraton On The Park, rejecting assurances from the government the deal will be both positive and transformative for the region.
Protester Vivien Nguyen said leaks have made her fearful the negotiations are not in the interest of Australians.
"This deal would give all the power to corporations and reduce government's ability to legislate in our public interest," she said.
"The text we've seen through leaks hasn't been reflected through assurances."
The trade deal has been negotiated largely in secret since talks started in 2008.
Doctor's Without Borders (MSF) has accused the US of attacking access to life-saving medicines via its push for pharmaceutical companies to have longer monopolies over brand name drugs as part of the TPP.
MSF says it will make it harder for generic companies to produce cheaper drugs.
Earlier, Mr Robb dismissed fears the price of medicine would go up.
"Those who are opposed to this scheme for all sorts of reasons are peddling a lot of misinformation, saying pharmacy costs will go up," he told ABC Radio.
"This is not the intention or the outcome that will occur with this particular 21st century agreement."
