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