Carvana Co. has adopted a "poison pill" to limit shareholders from raising their stakes and has reached an agreement to sell up to $4 billion of auto loans, the struggling used car retailer said yesterday, Reuters reported. Ally Bank and Ally Financial will buy the loans, the company said, giving Carvana a fresh source of funding as it tries to restructure its operations. Carvana said the "poison pill" will help safeguard its "significant" U.S. federal net operating loss (NOLs) that could be available to offset its future taxable income. The company's ability to use the NOLs would be substantially limited if its 5%-shareholders increased their ownership, Carvana said.