Jim Cramer's Stop Trading! Sell Valero

"I have had enough of Valero (VLO - Cramer's Take - Stockpickr - Rating)," Jim Cramer said Friday on CNBC's Stop Trading! segment.
Cramer said the refiners have had a good run but that the run may well be over, what with margins peaking and the summer driving season around the corner. Cramer said "you can't own these" with margins peaking, so he's selling the group.
Cramer is also lightening up on Chevron (CVX - Cramer's Take - Stockpickr - Rating), which he said has had a good rally but may be tapped out for a bit.
Cramer likes investment bank JMP (JMP - Cramer's Take - Stockpickr), saying it's a good firm without a lot of risk at its $11-a-share initial public offering price. Cramer said the smaller investment banks are "sleepers."