It's never a great day when analysts start pulling back from their bullish calls, and Friday brought a wave of downgrades across several major names. Here's what Wall Street's top research analysts are thinking now.

Veeva Systems Loses Its Bull

Keybanc analyst Scott Schoenhaus downgraded Veeva Systems Inc. (VEEV) from Overweight to Sector Weight, abandoning his previously optimistic view on the healthcare software provider. Veeva shares closed at $229.49 on Thursday.

PayPal Takes a Double Hit

Baird analyst Colin Sebastian wasn't pulling punches with PayPal Holdings Inc. (PYPL), downgrading the payments giant from Outperform to Neutral while simultaneously slashing his price target from $83 to $66. That's a meaningful haircut for a stock that closed at $61.69 on Thursday, suggesting limited upside even from current levels.

Valero Energy Gets Mixed Signals

In a somewhat confusing move, Mizuho analyst Nitin Kumar downgraded Valero Energy Corp (VLO) from Outperform to Neutral but actually raised the price target from $190 to $192. The energy company's shares closed at $171.91 on Thursday, still well below that target despite the downgrade. Sometimes analysts are saying "we like it, just not as much as we used to."

Forge Global Cools Off

Citizens analyst Devin Ryan downgraded Forge Global Holdings Inc. (FRGE) from Market Outperform to Market Perform. The private securities marketplace saw its shares close at $44.45 on Thursday.

BOK Financial Joins the List

Rounding out the downgrade parade, Hovde Group analyst Brett Rabatin cut his rating on BOK Financial Corp (BOKF) from Outperform to Market Perform. The regional bank's shares closed at $120.56 on Thursday.

These rating changes reflect shifting sentiment among Wall Street's research teams as they reassess their expectations for these companies heading into the new year.