The first case alleges six defendants used insider information and in some cases players altered their performances to manipulate bets. The second involves 31 defendants accused of participating in rigged illegal poker games
The alleged perpetrators include members of organised crime families, officials say, with defendants accused of using special contact lenses and X-ray poker tables to read others' cards
FBI Director Kash Patel says the "mind-boggling" fraud involved tens of millions of dollars across many years .Officials outlined the charges in detail at a news conference earlier - read a summary here
In relation to the basketball betting investigation, the main markets mentioned during that FBI briefing were to do with player props.
In sports betting, specifically basketball in this case, props are where, ahead of a game, a bookmaker will give predicted values for a player based how they are likely to perform.
These include points, assists and rebounds, while other statistics in basketball can also be bet on. Bettors are offered the chance to bet on players to get over or under the prop given, which is intended be at a value which is likely to be even chance.
The pre-determined props are based on factors such as that individual player, their form, the level of the opposition, their skill set and also market movement.
For example, if a player has a points prop of 20.5 points, it means bettors will have the chance to bet on that player to score either more or less than 20.5 points in the match.
The case unveiled today involves members of New York's most notorious crime families, including the Bonanno, Genovese, and Gambino.
The Five Families - the Bonanno, Colombo, Gambino, Genovese and Lucchese - have ruled the city's Italian American mafia since 1931.
Major mob takedowns reduced the prevalence of mafia activity in the 1990s, aided by the Racketeer Influenced and Corrupt Organizations (RICO) Act and then-mayor Rudy Giuliani. But, as today's indictments show, the mafia has not entirely gone away.
The Five Families are part of the larger American-Sicilian mafia operation known as La Cosa Nostra, which translates to "this thing of ours", and the members often work closely with their counterparts in Sicily.
On the Italian side, the gangsters consider New York City to be a "gym" where their members go to be toughened up, criminology professor and modern organised crime expert Anna Sergi, previously told BBC.
Sports betting was outlawed in most of the US from 1992 until 2018, when the Supreme Court turned regulation of the practice over to the states.
That didn’t mean it didn’t happen informally of course.
But since the federal ban was struck down, the practice has exploded, with major sports leagues and media companies making deals with gaming firms to get in on the action.
In the first eight months of the year, Americans wagered nearly $100bn on sports through official channels, up roughly 12% compared to 2023, according to the American Gaming Association.
The embrace of sports betting has been part of a broader shift in approach to gambling in the US, which for decades was largely limited to Native American lands and the Nevada’s Las Vegas strip.
Sports betting in particular was viewed with suspicion due to a 1919 baseball World Series match-fixing scandal. For years, many leaders of major sports leagues in the US opposed legalisation, worried it would erode trust in its games.
We just heard from federal and local law enforcement officials after several US basketball figures, including a current coach and player, were arrested in two wide-ranging investigations involving the mafia.
More than 30 people have been arrested in a sweeping investigation into fraudulent sports gambling and betting that began several years ago
The investigations included alleged illegal and rigged gambling activities in which the perpetrators used special technology including contact lenses to read cards, manipulate shuffles, and communicate with others
They enticed their victims with the prospect of playing alongside notable individuals including athletes, officials say
Charges include wire and crypto fraud, money laundering, extortion, and armed robbery, officials says
Another scheme involved players using privileged information to help others bet on their games
In one case, NBA Terry Rozier is suspected to have feigned an injury during a game, information he is alleged to have passed on before the game started
Victims lost about $7 million (£5.2 million) in the schemes. One person lost over $1 million, officials say
Officials says the National Basketball Association is cooperating and that college basketball games were not part of this investigation