Around 15m shares in St Helens-based Pilkington had changed hands by mid-afternoon after rumours that Japanese rival Nippon Sheet Glass was circling the group.
This pushed shares in the company up 5% to 134p, their highest level since 2000, and followed heavy trading in the stock at the end of last week.
A spokesman for Pilkington declined to comment on the rumours which have swirled around the firm for the past two years and have helped to double its value to £1.66bn.
Nippon, one of the world's biggest glass-makers, is seen as a likely bidder because it is the largest shareholder in Pilkington with a near-20% stake.
Its UK subsidiary, NGF Europe, is also located in St Helens where Pilkington's head office is based.
Traders thought the bid link had been revived by the likelihood that French glassmaker St Gobain will this week launch a hostile takeover campaign for UK plasterboard manufacturer BPB.
Consolidation in the sector could force Nippon to make the next takeover move in the knowledge that competition issues would rule out any of its major European rivals from mounting a bid for Pilkington.
However, analysts pointed out that Nippon lacked any international management and would need to persuade Pilkington bosses to remain with the company if it was to make a successful bid.
Pilkington employs about 24,000 people and has plants in Birmingham and Doncaster. The company manufactures in 25 nations and has sales and distribution operations in more than 130 countries.
In May, the company posted a 26% rise in annual profits to £180m as efforts to refocus the business around the automotive and construction sectors continued to pay off.
Pilkington has cut around a third of its workforce over the past decade in a bid to become more competitive. It then concentrated on using its infrastructure, such as machinery and factories, more efficiently.
But the company has faced challenges in past months from rising energy prices and price deflation in some European markets.