An institutional investor’s multi-billion dollar bullish bet on US stocks has become the talk of the options market.

Over the past month, market participants have noted steady buying of mostly June 2027 call options across a swath of large US companies. Estimates vary of the total premium being spent, with Nomura Holdings Inc. tallying nearly $3 billion.

Many of the bullish-long term bets were placed on technology megacaps, and come as the Nasdaq 100 has rallied 24% since April 8 as part of a broader surge in US stocks. The options, which are around the stocks’ current market levels, can gain in value as shares rally, and also if volatility increases. While short-term measures of market swings have retreated following the early-April spike, 60-day volatility in both QQQ and SPY are holding around the highest levels in nearly five years.

Chris Murphy, co-head of derivatives strategy at Susquehanna International Group, speculates that the buyer is a deep pocketed and broadly optimistic investor happy to own options that will likely rise in value if volatility increases.

The trades are being done by a “big global macro player who is long term bullish and wants the optionality and volatility exposure of long calls as opposed to buying equities,” he told Bloomberg.

The options buyer spent $316 million for at-the-money calls on Amazon.com Inc., $159 million on similar options on Salesforce Inc. and $878 million on ARM Holdings Plc, according to data from Nomura. Amid the option-buying spree, implied volatility for two-year options on the Nasdaq 100-tracking Invesco QQQ Trust ETF rose to the highest level since January relative to the SPDR S&P 500 ETF .

Since the options are years away from expiring, the premium is far higher than for the shorter-term contracts — zero-day-to-expiry in particular — that have driven much of the trading. For instance, 2,200 ARM June 2027 $130 calls traded for $47.40 on Wednesday. While that totals $10.4 million in premium, the volume is just 0.2% of overall open option positions.

While it’s difficult to say for sure that it’s a single investor, the repeated pattern of buying lines up with one party building up most of the position, with others possibly copying the trades.

The call buying “has just been SPECTACULAR,” Nomura cross-asset strategist Charlie McElligott wrote Wednesday in a note to clients.