NEW YORK, July 10 Reuters Investors are piling into bullish options bets on the shares of Rivian Automotive, with some market participants saying the buying has helped the electric vehicle EV maker39;s stock notch a record nineday winning streak.

Rivian shares, which took off last week after the company reported betterthanexpected quarterly vehicle deliveries, have risen 83 over the last eight trading sessions. Some 831,000 Rivian options contracts traded on Monday, or two times its average daily volume.

Much of the options trading has consisted of investors buying super shortdated calls, said Daniel Kirsch, head of options at Piper Sandler, adding that the options activity had helped drive Rivian39;s shares higher.

Large purchases of outofthemoney call options contracts that are not profitable but stand to gain in value as the stock climbs can sometimes give an additional lift to a stock39;s price.

Such a phenomenon sometimes called a gamma squeeze  occurs when market makers who sold the call options hedge their risk by buying the underlying stock, helping push the share price higher as a result. The phenomenon has occurred with shares of various companies popular with options buyers over the last few years, from AMC to Tesla.

It reminds me a lot of what people would do with Tesla when it was going up every day … buying the shortest dated outofthe money calls and trying to get it to ramp higher, Kirsch said, noting that Rivian39;s options trading was driven by…