Chipmaker Broadcom Inc (AVGO.O) said on Thursday it would buy back up to US$12 billion of its common stock, sending its shares up 4.5 per cent to US$250 in extended trading.

The company, which last month ended its efforts to acquire rival Qualcomm Inc (QCOM.O), said the repurchase program is effective immediately until the end of Broadcom's fiscal year 2019.

Broadcom moved back to the United States from Singapore earlier this month, following U.S. President Donald Trump's decision to block its US$117 billion offer to buy Qualcomm on national security concerns.

The San Jose, California based company has about 411 million outstanding shares and a market value of about US$98.71 billion as of Thursday's close.