Cardtronics Inc., the world's largest ATM ISO based on the number of machines owned and managed, has seen an 8% decline in the size of ATM withdrawals in the United States because of the economy, according to an analyst report released Tuesday by William Blair & Co. The decline indicates consumers are curtailing spending in the weaker economy. However, the number of ATMs transactions has not declined, the report says. "Cardtronics earns revenue based on the number of transactions, not the size of the withdrawals," William Blair says. As the economy weakens, Cardtronics executives expect consumers to manage their personal finances more tightly by using cash more frequently at the expense of credit, William Blair says. Houston-based Cardtronics owns and manages more than 32,000 in the United States, Mexico and the United Kingdom.