Reich & Tang Asset Management interview questions

TL;DR: Positive interview experience, but the company rescinded a signed offer after I gave my two-week notice. I was contacted by a third-party recruiter who discussed my experience and the job opportunity. I applied and received a technical HackerRank interview, which consisted of 3 SQL problems, 2 algorithm problems, 1 .NET problem using an IDE, and 3 multiple-choice questions. The camera was on, so I would suggest not having another laptop open. The algorithm problems were of easy to medium complexity. I think I got most of them right, but not all. Afterwards, an in-house recruiter reached out to set up a standard HR interview. After passing that, I had an interview with the manager and two developers. This interview was both technical and behavioral, covering .NET, OOP questions, and my background on various projects. After passing that, I had an interview with the VP, which was more behavioral and focused on my experiences and what they expected for the role. The VP was enthusiastic about tech, and it was a great conversation if you like software development. I received an offer, but it was a bit low for the market and my experience. My third-party recruiter delayed conveying my dissatisfaction with the offer, but eventually, I was able to negotiate a slightly higher salary. I signed the offer and was waiting on my background check. I asked if I could extend my start date by 1-2 weeks since the background check took more than two weeks. They said they couldn't, and I agreed to the original start date. So, I gave my two-week notice to my current employer. Two days later, they rescinded the offer through the third-party recruiter, not even with an official email. I was told it was because I asked to move the start date, although I had agreed to the original date. I didn't understand what happened. I emailed the VP, stating I thought there was a misunderstanding, but my third-party recruiter told me not to contact them anymore. It felt like a very cowardly move from the company, and they really screwed me over. Thankfully, my current employer let me take back my two-week notice. If you already have a solid job, I wouldn't even remotely entertain this place, as they can rescind a signed offer.