Former Union Finance Minister Yashwant Sinha said on Sunday that the introduction of GST and demonetisation affected the Indian economy adversely. He was speaking at an interactive session organised by the All India Professional Congress here. The Indian economy is passing through one of the worst phases since banking, farming, employment generation and other sectors are in the doldrums. Demonetisation was a monumental failure, leaving small and medium traders, the informal economy and job seekers in the lurch, he said.