I think the title might seem rather elementary, but nothing in market analysis is really too complex. When the market is rising with great breadth and broad participation it tends to be longer-lasting and stable. Recall that post-election we witnessed some amazing rally days, market breadth very strong and equally strong turnover. That basics - a market rallying on higher volume and participation can lead to higher prices.
Of course, nothing is a guarantee. Yet, we follow trends and patterns that repeat over and over again. Lately, some of the best names that have been leading the market since the election have fallen sharply. Witness the banks/financials, which have faltered badly since the recent Fed action (rise in short term rates). Many believed that would help banks, but when rates on the long end of the curve headed lower that flattened out the yield curve, and banks are not attractive in that environment.
Further, commodity names have been hit hard of late, strong days are not followed up with any conviction. This is a concern as well, and with crude oil getting hammered there are related groups that continue under distribution (selling). Tech and biotech have been safe havens, but those groups cannot push markets up forever. Even more, transports have come under significant pressure, breaking support levels in short order. Lastly, home builders have declined sharply as a group.
As we move into the new quarter next week, we'll have to be mindful of which groups lead and which ones are lagging. The markets will take the cue from the leaders who participate. If the groups that lead growth and expansion in markets show leadership with broad expansion we could see that next leg higher starting the new quarter. However, a lack of sponsorship from leading names may cause market participants to take a pause.