Multiple Wall Street firms have made bullish calls for the capital return program in recent weeks.
Morgan Stanley analysts expect Apple, which has the biggest overseas bank account of any S&P 500 company, to increase the capital return program by $150 billion.
"This would imply Apple repurchases $210bn in shares and pays $52bn in dividends over the next three years," Morgan Stanley equity analyst Katy Huberty wrote in a note to clients in April. Huberty said this would still leave about $30 billion on the table for acquisitions.
"We expect a meaningful uptick in Apple's capital return program on May 1st," she said.
British newspaper The Times reported that the increase could be as much as $400 billion, citing "several analysts."
Citi Research predicted earlier in April that Apple will use tax reform proceeds to increase its stock buyback and dividend program by as much as $100 billion.
"Looking ahead, we expect investor focus to be on the impact from Apple's capital returns strategy, which we estimate could be a $100 billion increase, the 2H18 lineup, and continued strength in Apple's Services segment," analyst Jim Suva wrote in a note to clients.
Longbow Research was also optimistic for the capital return expansion. The firm predicted in April that Apple could double its dividend and have its payout level still be in line with its large technology competitors.
"We see Apple substantially increasing its capital return program given the incremental cash provided from U.S. tax reform and Apple's pledge to reduce its net cash position to zero over time," analyst Shawn Harrison wrote in a note to clients. "Apple should double its dividend to align its payout ratio to that of large-cap tech peers."
Daniel Ives, head of technology research at GBH Insights, said in January that large U.S. tech companies will repatriate $300 billion to $400 billion in 2018, with Apple making up $200 billion of that amount.
"We believe accelerated buybacks, another dividend hike, and potentially larger M&A will be the trifecta of benefits shareholders could expect to see in 2018" for Apple, Ives wrote in a note to clients.