BUENOS AIRES (Reuters) -Argentina's long-suffering markets gave a slightly weary cheer on Monday after the country sealed a $20 billion loan program with the International Monetary Fund and undid large parts of its currency and capital controls late on Friday. The peso slid around 9% to 1,170 per dollar, but less than expected, while widely-used parallel exchange rates strengthened, almost closing the gap between the official and informal rates that has widened sharply in recent years. The currency drop came after the central bank undid its so-called crawling peg and allowed the currency to float freely within a far wider trading band of 1,000-1,400 pesos per dollar, a major policy shift investors and firms had been pushing for.