Unusual Options Activity: Bullish Trade on Solar ETF

We noticed some bullish activity Wednesday on the Invesco Solar ETF (TAN). So far, the May 44 and May 49 calls have each traded more than 10,000 contracts, outstripping open interest at each strike by a wide margin. These contracts have been moving in matched lots with the 44s moving at or near the ask while the 49s are moving at or near the bid. This indicates this is likely a bullish debit spread being opened.