Nonetheless, some studies show that share repurchases do not have any significant impact on liquidity. For example, Singh et al. (1994) used a sample of National Market System (NMS) listed stocks to examine the changes in bid-ask spreads surrounding open market stock repurchase announcements. They find no result showing the significant effect of share repurchases on liquidity. In particular, they find a significant increase in bid-ask spreads prior to the announcement day but no further change in bid-ask spreads.