The UK's competition watchdog had opened an in-depth probe in March after warning that the deal risked harming competition.
Avast a stock market capitalisation of about $8.5 billion (roughly Rs. 67,260 crore)
UK regulators on Wednesday gave the provisional nod to US cyber security giant NortonLifeLock's $8-billion (roughly Rs. 63,320 crore) purchase of Czech rival Avast, whose London shares surged more than 40 percent in reaction.
The Competition and Markets Authority (CMA) watchdog had opened an in-depth probe after warning in March that the deal risked harming competition.
However, the CMA concluded in initial findings published on Wednesday that this was not the case.
"Millions of people across the UK rely on cybersafety services to keep them safe online," said Kirstin Baker, chair of the CMA inquiry group, in a statement.
"After gathering further information from the companies involved and other industry players, we are currently satisfied that this deal won't worsen the options available to consumers."
She added that the CMA has therefore "provisionally concluded that the deal can go ahead".
In reaction, Avast's London stock surged 42.41 percent to 680.60 pence on the British capital's falling market.
That gave Avast a stock market capitalisation of about $8.5 billion (roughly Rs. 67,260 crore).
The regulator found both businesses "face significant competition", particularly from main rival McAfee but also from smaller suppliers.
In addition, Microsoft's built-in security applications on its Windows operating system provided "increasingly important alternatives" for consumers.
NortonLifeLock said it "welcomed" the news, adding in a separate statement that it hoped to complete the deal by September 12, pending final CMA approval.
The pair had announced the blockbuster takeover last year to create a leading consumer business as Internet activity boomed during the pandemic.
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