Investors who invested in the initial public offering (IPO) of the recently concluded primary market issue of Barbeque-Nation Hospitality were a worried lot on Wednesday when its shares made a tepid debut on the bourses. However, the same lot of people were a lot happier when the stock was locked in 20 per cent upper circuit at the end of trading. The stock with a face value of Rs 5 per share and issued at Rs 500 per share, listed at 2 per cent discount to its issue price at Rs 489.85, on NSE and ended 20 per cent up at Rs 587.90.