G'Day, Wall Streeters! I'm Aaron Weinman. If you hadn't guessed, I'm Australian, and one of our favorite responses when we don't want something is, "Yeah, nah." It's essentially, "Yes, maybe, but no, we'll pass."

I can't help but think Elon Musk is a "yeah, nah" kinda guy.

The enigmatic Musk said Twitter is breaching its $44 billion deal with the billionaire because the social-media company isn't giving him the info he needs around bots.

This isn't entirely surprising. Musk has tweeted about this before. But this time, he's backed up tweets by putting it in a shiny SEC filing and appointing lawyers from Skadden to argue his case. Twitter, meanwhile, has its own legal firepower.

It's the latest in the "will-he-won't-he" buy Twitter saga.

With that out of the way, let's get to today's news.

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1. Wall Street quants are cashing in their checks for innovative start-up opportunities. Take Krešimir Penavić. He joined hedge fund Renaissance Technologies in 1993 as a math programmer, and later became a research scientist.

Penavić left RenTech in 2016 with a parachute he described as "quite golden."

Since then, he's started a hospitality business in Croatia, which includes a winery, a villa, and a yacht. He also raced Ferraris in the Ferrari Challenge before selling his Prancing Horses.

But perhaps most importantly, Penavić in 2017 got an opportunity to put his mathematical wizardry to work on creating a cheaper alternative to LASIK eye surgery.

Krešimir Penavić is the first "quantrepreneur" to be profiled in a new series by Insider's Wall Street correspondent Alex Morrell. The series highlights innovative quant traders who ditched the Street to apply their skills to real-life problems.

Read the full feature here.

In other news:

2. First Trust rivals Vanguard when it comes to ETF-generated revenues. The firm's ETFs amassed $103 billion over the last 10 years. All while Brian Wesbury, its chief economist, tweets like a disgruntled fella on 4chan. Here's a look inside the burgeoning fund manager.

3. Bank of America is letting its vaccine holdout-ers back in its offices. BofA is allowing business lines to determine how often staff should frequent One Bryant Park, leading to a rather random sprinkling of staff around the office.

4. Tiger Global has been burned by depressed tech stocks. The fund bet on more startups than any other US investor last year, but it told investors last week that its hedge fund has dipped 52% this year.

5. Wall Street giants are all in on public-cloud tech. The software now touches many parts of the business from investment banking to risk management. Here are 14 execs leading that revolution from Bank of America to Blackstone.

6. Citi, meanwhile, plans to hire some 4,000 tech staff to help its institutional clients move online. More than 1,000 recruits will join the bank's markets tech team to help upgrade some archaic systems for both Citi's clients and staff.

7. Another day, another SoftBank-backed company comes under duress. Gifting startup Sendoso just announced layoffs as the tech world comes to grips with lower valuations. Here is the latest from the startup that raised $100 million last September.

8. Winter's coming for the crypto talent market. Fintech headhunters told crypto companies that they've got to get creative when it comes to landing talent as the market cools. Here are the key risks when it comes to these interviews.

9. JetBlue is channeling its inner Vito Corleone in its battle with Frontier to buy rival airline Spirit. The low-cost carrier improved its proposal to Spirit's board, and increased the reverse break-up fee by $200 million to $350 million.

10. Come get your fintech pitch decks (including Fundid). Capital for these upstart financiers more than doubled last year to $132 billion globally. Here's 41 (yep, 41!) decks from fintechs disrupting trading, investing, and banking.

Done deals:

• Bain Capital Private Equity has acquired cloud software provider LeanTaaS from Insight Partners.
• Middle-market investor Compass Diversified bought R&D company PrimaLoft from Victor Capital Partners.
• Capital Dynamics' private-credit business led financing for eatery WOWorks' acquisition of Barberitos Southwestern Grille and Zoup! The debt included a nifty metric that ensures the borrower's interest-rate will lower if it meets targets that encourage growth for minority-owned store locations.

Keep updated with the latest business news throughout your day by checking out The Refresh from Insider, a dynamic audio news brief. Listen here.

Curated by Aaron Weinman in New York. Tips? Email aweinman@insider.com or tweet @aweinman11. Edited by Hallam Bullock (tweet @hallam_bullock) in London.