Analysts had predicted that a so-called "supercycle" increase in iPhone sales, driven by booming demand for the more expensive new models, would push the company over the US$1t mark.
Although this has failed to materialise, with iPhone sales rising by just 3 per cent in the most recent quarter, rewards for shareholders and better sales of its other products have brought it close to the milestone.
Last month it unveiled a US$100b share buyback and a 16 per cent increase in quarterly profits, with growth driven by software sales and accessories such as the Apple Watch.
It has been racing rivals including Google's parent company Alphabet, Amazon and Microsoft to the milestone, but the nearest company in terms of market value, Amazon, lay at around US$815b yesterday.
On Monday, Apple had unveiled a string of software updates at its annual Worldwide Developers' Conference.
The new version of the iPhone's operating system will include features that limit the amount of time users can spend on their devices, performance upgrades and enhancements to Apple's "Siri" virtual assistant.
The company also limited how websites such as Facebook can track users' browsing habits, drawing a line between itself and advertising-funded internet companies.
Richard Windsor, an analyst at Edison Investment Research, said the company could "sit out the uncertainty presented by the current backlash against the use of data for monetisation purposes".
It came amid a broad rise in technology shares.
The Nasdaq index of technology shares hit an all-time high, boosted by strong growth from the so-called FAANG shares of Facebook, Apple, Amazon, Netflix and Alphabet.Shares in Asia's big five tech giants - Baidu, Alibaba, Tencent, Taiwan Semiconductor and Samsung - have also soared in recent weeks.
Apple's shares now need a rise of just 5 per cent for it to reach a US$1t valuation.