Alphabet (NasdaqGS: GOOGL) has expanded its SpaceX stake by nearly 4 million additional shares, lifting the holding’s value to about US$69b. The position has grown from an original US$900m investment, reflecting a very large increase in the implied equity value. Alphabet has agreed to pay SpaceX monthly for Nvidia GPU access that will support the Gemini Enterprise AI platform. Alphabet’s larger SpaceX stake and new AI infrastructure agreement are only one part of the wider story here. Our…