Both the scrips hit the circuit filters on the Bombay Stock Exchange (BSE) and National Stock Exchange (NSE). Sterlite's announcement to hike its offer price to Rs 221 and its stake in Indal to 52.03 per cent from the original stake of 20 per cent as well as Alcan's revised bid came as a surprise to market players.

Indal attracted a circuit at the upper end at Rs 151.30, with volumes of around 4,000 shares. It closed at Rs 151.40 on the NSE but was frozen at that level. On the BSE, the scrip ended at Rs 151.30 as against its previous close of Rs 137.60.

Sterlite hit the upper end of the circuit filter at Rs 353.50 on the NSE, moving up from the previous close of Rs 321.90. However, it lost steam at the end of the day and moved out of the circuit filter to close at Rs 350.10, recording an increase of eight percent over its previous day's close.

On the BSE, the scrip closed at the circuit level of Rs 347.50 and saw a volume of around 7.57 lakh shares.

There were no quotes on the kerb market in both the scrips as the dealers expect the shares to open at the circuit filter prices on Tuesday.

The general feeling in the market was how the two companies could hike their offer prices to such an extent. Sterlite has increased its offer prices by almost 92 per cent. Alcan, too, has increased its offer substantially. Brokers were also debating Sterlite's decision to raise its stake to 52.03 per cent in Indal as against its earlier decision to acquire only 20 per cent stake.

According to an analyst at Pranav Securities: "It is quite surprising that both the companies decided to raise the offer by such a huge amount. It has raised doubts on what the companies know that the market does not know. Is the budget going to have something attractive for the aluminium industry?" "It sounds more like a prestige issue forSterlite now," said a prominent dealer on the BSE.