Shares of Gitanjali Gems on Tuesday tanked for the fifth straight trade session, a day after two senior officials of the company -- Chandrakant Karkare and Pankhuri Warange -- resigned following the unravelling of $1.8-billion Punjab National Bank (PNB) fraud.The stock closed 9.91 per cent lower at Rs 30.45 per share.However, shares of PNB exited from the negative territory and closed 0.13 per cent higher at Rs 116.55.At one point, the shares had plunged to the day's low at Rs 111 per share after global rating agency Fitch placed the lender's Viability Rating of 'bb' on Rating Watch Negative (RWN) following the multi-crore fraud detected in the bank.The shares of the two companies had started to decline following the country's second largest state-run bank PNB's declaration of unearthing a fraud of Rs 11,300 crore involving diamantaire Nirav Modi.The fraud, which included money-laundering among others, concerned the Firestar Diamonds group in which the Central Bureau of Investigation (CBI) booked Modi, his wife Ami, brother Nishal Modi and uncle and business partner Mehul Choksi -- the promoter of luxury jewellery brand Gitanjali Gems.The CBI on Monday sealed the Brady House Branch of the bank as multiple probe agencies continued with their probe into the multi-crore fraud.