Mumbai, Sept. 17 -- The BSE Sensex on Thursday dropped by 150 points at 39,148.57 in opening trade, after two days rally as selling was seen in Telecom, Power, Realty and Finance stocks.

The Nifty of National Stock Exchange too fell by 36.05 points to 11,568.50.

IT services firm Happiest Minds Technologies, which concluded its initial public offering last week on a remarkable note, will make stock market debut.

The Rs 702-crore initial public offering of Happiest Minds Technologies, promoted by Ashok Soota, garnered massive response from investors as it was subscribed a whopping 151 times.

The price band for the offer, which closed for subscription on last Wednesday, was fixed at Rs 165-166 per equity share.

The Sensex registered intra...