The recent special bulletin brought out by the NSE on the occasion of the index touching 10,000 had an interesting comparison over the last 12 years time frame. Back in 2005, the weightage of banking and financial services in the overall Nifty was just about 12%, with automobiles, oil and IT having around the same weightage in the index. By 2017, this situation had changed drastically. While the other 3 sectors have lost weightage share in the Nifty, the banking and financial services now account for 35% of the weight in the Nifty. That can be partly attributed to more banks joining the index but is also largely explained by the growth in the value of banking stocks.                                                                                                                       
                                                                                                                              Source;-Angel Broking Blog.