The local benchmark began nearly 180 points higher and soared more than 500 points at one point. It later pared some of the gains and ended 448 points, or 1.6 percent higher, at 27,963.
Market turnover was HK$155.7 billion.
Heavyweight Tencent rallied 3.9 percent, after antitrust regulators in the mainland approved its plan to take search engine Sogou private.
Other tech shares also had fared well. Alibaba jumped almost four percent. Meituan advanced 3.4 percent. Xiaomi added 1.3 percent.
HSBC rose 2.6 percent, after the Bank of England removed its curbs on dividend distribution and share buybacks, which were imposed last year to protect lenders from pandemic shocks.
The biggest blue-chip gainer was Geely Auto, which soared 5.2 percent.
Across the border, the Shanghai Composite Index was 0.5 percent firmer, while the blue-chip CSI300 index inched up 0.2 percent. The Shenzhen Composite put on 0.3 percent.
Elsewhere, Japan’s Nikkei added 0.5 percent. The Kospi in Seoul gained 0.8 percent. Taiwan was up 0.2 percent. Singapore edged up about 0.6 percent. But Australia was flat.