(Reuters) - At a grilling by lawmakers over the frenzied trading in retailer GameStop, Keith Gill, a YouTube streamer known as Roaring Kitty, hedge fund managers and the head of Robinhood and Reddit defended their actions. Those testifying were Robinhood CEO Vlad  Tenev, Melvin Capital CEO Gabriel  Plotkin, Citadel CEO Ken Griffin and Reddit CEO Steve Huffman. Here are the testimonies here of the players involved and a link here to biographies of some of them. Some quotes from the hearing: “A few things I am not. I am not a cat. I am not an institutional investor, nor am I a hedge fund. I do not have clients and I do not provide personalized investment advice for fees or commissions. I am just an individual whose investment in GameStop and posts on social media were based upon my own research and analysis.” “Investing can be risky and my approach can be risky but for me personally, yes (I would buy GameStop now). Yes, I do find it attractive at this price point.” “My investment in Gamestock was based on the fundamentals.” “Increased transparency could help. That someone like me could have a better understanding of how those things work ... would help retail investors.” ROBINHOOD CEO VLAD  TENEV: “We always felt comfortable with our liquidity... The additional capital we raised wasn’t to meet capital requirements or deposit requirements... ” “I recognize customers were very upset (from the restrictions on trading)... it would have been significantly worse if we had prevented customers from selling.” “Not at all, zero pressure (from anyone on the panel to decide to restrict trading), it was a collateral depository decision.” “I’m sorry for what happened. I apologize. I’m not going to say that Robinhood did everything perfect and we haven’t made mistakes in the past, but what I commit to is making sure that we improve from this, learn from it, and we don’t make the same mistakes in the future. And Robinhood as an organization will learn from this and improve and make sure it doesn’t happen again, and I will make sure of that.” “I do believe that the ability for the same share to be shorted an indefinite number of times is somewhat of a pathology and that should be fixed and I think step one of that is modernizing the antiquated settlement infrastructure that everything is built on. We simply don’t have the ability to properly track which shares have been shorted and how many times as they are moving through our settlement system.” “Robinhood owns what happened and we need to make sure it doesn’t happen again but Robinhood Securities had limited options and I believe the team did the right thing and the only thing. “Payment for order flow is one of our largest revenue sources. Yes (it is the largest.)” CITADEL CEO KEN GRIFFIN “As I was trying to explain... the quality of the execution varies by the channel of the order, this is a commonly understood phenomenon in economics.” “We have fought for 15 years to make that the basis by which orders are allocated because we strongly believe Citadel is better to provide better execution for retail orders in the long run.” “We are able to share our trading acumen with retail investors, give them a better price and give payments for orderflow to firms like Robinhood. “This has been very important for the democratization of finance.” “I believe that the short interest in Gamestop was exceptional. I’m not sure it’s worth us delving into legislative corrections for a very unique situation.” “We of course are talking to Robinhood as we manage a substantial portion of their order flow. “Absolutely not (whether they contacted Robinhood about restricting trading in GameStop).” “We don’t own DTCC. We are not party to the discussion/ dialogue between DTCC and Robinhood. We have literally nothing to do with DTCC other than being a member of DTCC... Citadel Securities owes a duty of best execution for every order that comes from Robinhood and I’m proud of how seriously our team takes that best execution.” MELVIN CAPITAL CEO GABRIEL  PLOTKIN “I think it is a really good question (regarding more reporting around shorting). It is not for me to decide. But if those are the rules then I will certainly abide by them.” “Anytime we short a stock, we locate a borrower. Our systems actually force us to find a borrower.” “In 2014 at our inception (we took a short position in GameStop) “I dont remember (what it was worth) at the time. Maybe $40. We believed the company had a lot of structural challenges. “Our systems won’t allow that (a naked short position) so it wouldn’t be possible to do.” REDDIT CEO STEVE HUFFMAN “We spend a lot of time at Reddit ensuring the authenticity of our platform. So we’ve got a large team dedicated to this exact task. Everything on Reddit - all of the content is created by users, voted on by users and ranked by users, and we make sure that that is authentic, and as unmanipulated as possible. And in this specific case, we did not see any signs of manipulation.”