Snap (SNAP) went public on March 2. The few analysts who had weighed in on the stock had nothing but cautious things to say, issuing only “sell” and “hold” ratings.

But don’t be surprised to see more optimistic ratings 25 days after the IPO date, which is when analysts from larger banks are expected to release ratings of their own.

Conflicts and the blackout period

Major Wall Street banks often do business with the very companies their analysts are covering, creating a potential conflict of interest that could result in these higher ratings. Furthermore, the potential conflicts are exacerbated because these analysts need access to the companies they’re covering and they might get shut out if they issue a “sell rating.”

When it comes to initial public offerings, analysts who weigh in with ratings fall into two buckets: those from independent research firms or smaller banks like Morningstar and Susquehanna, and those from larger institutions like Morgan Stanley (MS) and Goldman Sachs (GS). Because independent firms and smaller banks are usually unaffiliated with the companies their analysts weigh in on (in this case, Snap), they’re more free of conflicts and they can issue reports whenever they please, which is why we’ve already seen at least seven ratings trickle out.

With larger institutions, however, the situation becomes trickier because of the potential conflicts of interest. In this case, Goldman Sachs, Morgan Stanley, JPMorgan Chase (JPM) and Deutsche Bank (DB) have a vested interest in Snap, having been involved in Snap’s IPO.

These banks made millions from Snap’s Wall Street debut but also plan on having their analysts issue “buy,” “sell” or “hold” ratings on the stock 25 days or so after the the IPO date. The big banks haven’t been legally required to adhere to this “quiet period” for emerging-growth companies since the JOBS Act passed in 2012, but they often wait for 25 days to avoid potential lawsuits from other investors or outside parties alleging conflicts of interest.

CEO to analyst: “I’m not going to answer you”

However, these conflicts may still exist. The banks would argue they do not, due to firewalls established between the research departments and banking divisions of Wall Street firms, intended to prevent this very sort of thing from happening. But reality can play out differently.

“When affiliated analysts are allowed unfettered access to a company, they’re more likely to have more optimistic ratings,” explained Matthew Gustafson, assistant professor of finance at Pennsylvania State University.