Mumbai, Aug 29 (PTI) : Mirroring the turnaround in rupee, stock markets on Thursday soared with the S&P BSE benchmark Sensex logging its best gain in a week of nearly 405 points to end at 18,401.04 on across-the-board buying after RBI opened a special window to help PSU oil firms meet daily forex needs.

The gains in the 30-share bluechip index were led by RIL, HDFC, ITC and TCS that jumped in the 2-6 per cent range as investors chased shares beaten down in the recent bear run, amid expiry of monthly derivative contracts.

Investors became richer by Rs 1 lakh crore.

After a solid start, the Sensex remained in the positive zone for the entire session and ended 404.89 points higher, or 2.25 per cent, at 18,401.04. This is the best gain since 407-point rise on August 22.

Buoyed by RBI’s move to provide dollars directly to oil marketing companies, the rupee rose to 67.30 per dollar in intra-day trade after touching all-time low of 68.85 in the previous session.

Brokers said a firming global helped domestic markets as investors awaited US second quarter GDP data.

The broad-based National Stock Exchange index Nifty rose by 124.05 points, or 2.35 per cent, to end at 5,409.05 led by stocks of refinery, metal and FMCG sectors. Also, SX40 index, the flagship index of MCX-SX closed at 10,849.51, up 219.46 points or 2.06 per cent.

Shares of state0owned oil marketing companies, IOC, HPCL and BPCL, rose modestly after the RBI announced opening of a special window to help the three firms needing about 8.5 billion dollars every month to meet daily forex needs in a bid to check the rupee’s free fall. The rupee depreciated over 25 per cent against the dollar in 2013.

Sectorally, the oil and gas sector index gained the most rising 2.86 per cent to 8,094.62, followed by metal index by 2.38 per cent to 7,947.85. FMCG index rose by 2.29 per cent to 6,246.34 and capital goods index by 2.20 per cent to 7,096.23.