Question: when do you need a medallion signature guarantee
[{'answer': 'for the transfer of securities', 'provenance': [{'wikipedia_id': '1461364', 'title': 'Medallion signature guarantee', 'start_paragraph_id': 1, 'start_character': 87, 'end_paragraph_id': 1, 'end_character': 117, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]