Following JPMorgan Chase's spectacular trading loss, CEO Jamie Dimon is still on the hot seat to explain what happened. Today, on the second-quarter investor conference call, analyst Mike Mayo asked particularly difficult questions.

Mayo asked "if the firm as a whole has reached some sort of tipping point in terms of bigness or complexity that makes it more difficult to manage than in the past." Dimon responded, "No." Mayo followed up by asking whether Dimon has "lost a step," and someone yelled, "Are you getting old?"

Dimon focused on the firm's successes through the recession and in assimiliating Bear Stearns and Washington Mutual. He claimed that the issue is a marketing problem.

However, Dimon did admit, as he had before, "We made the mistake," but also said, "I cannot prove a negative." To regain trust, Dimon emphasized the firm's current structure: "We believe we've got very good controls and very good people in place."

Dimon focused on the bank's results, and Mayo acknowledged the positive returns but said, "But we saw how the sausage is made, and it just makes me wonder if I'm going to get food poisoning in the future."

Discussion Starters:

• Listen to the exchange between Mayo and Dimon. What's your assessment of Mayo's interview strategy? What are his most and least effective questions?
• What are Dimon's most and least convincing arguments?