Mumbai, Aug. 18 -- The Indian rupee appreciated 23 paise to close at 87.36 (provisional) against the US dollar on Monday, supported by strong domestic equities. Indian shares rose sharply on Monday after Prime Minister Narendra Modi unveiled plans of the biggest tax overhaul since 2017 over the weekend, boosting stocks across sectors like auto, financial, real estate, consumer and cement. With robust GST collections and a broad tax base, government sources indicated that nearly 90 percent of the items in the 28 percent slab will now move to 18 percent. S&P upgraded India's rating to BBB, from BBB- with a stable outlook last week and said the economy's growth prospects won't be derailed by U.S. President Donald Trump administration's 50 pe...