Approvals for a potential COVID-19 vaccine later this year could threaten the recent surge in speculative investment in big U.S. technology companies and pull investors back towards more traditional growth-linked cyclical stocks, according to analysts at Goldman Sachs.

Seen as "stay-at-home" winners in the coronavirus lockdowns, shares in Apple Inc and Alphabet have surged this year and now account for nearly a fifth of the S&P 500's stock market value.

Bumper results from the iPhone maker last week pushed it past Saudi Aramco to become the world’s most valuable publicly listed company and heading towards a $2 trillion valuation.

In a global markets research note sent to clients, Goldman analysts said the current rally could last until Labor Day in early September, but would be threatened by updates on vaccines.

“Approval could ... prompt the kind of rotation that started and petered out in May and early June, supporting traditional cyclicals, steeper curves and banks, and challenging tech leadership,” they argued.