Mohamed El-Erian, chief economic adviser at Allianz, is warning that lower-income Americans are under "significant pressure" and that a halt to their spending would weigh on the economy as a whole. "This is not an isolated concern if the lower household incomes stop spending, not because they don't want to spend, but they're not able to spend. That will contaminate upwards for the economy as a whole," El-Erian said in an interview during Yahoo Finance's annual Invest conference. The economy has become increasingly bifurcated as higher-income consumers continue to spend while lower-income households have been ... (full story)