When oil dropped below $50 a barrel early last year, Diamondback Energy chief executive Travis Stice dialed Rob Santangelo’s cellphone.
The energy executive was worried about carrying debt as oil prices fell and wanted to raise cash to pay it off by selling more stock. Diamondback's shares had fallen by one-third in the preceding several months, and oil markets were in retreat. But Santangelo, a Credit Suisse banker who had shepherded several offerings of Diamondback's shares, thought a sale could be done.
