In a post-earnings research note titled "The Math Still Matters," JPMorgan analyst Stephen Tusa says he came away from the General Electric's Q4 scratching his head at the stock reaction. Shares of GE closed yesterday up 12%, or $1.06, to $10.16.

The analyst attributes the rally to the company's "incrementally better" free cash flow, the "nominal nature" of the Q4 insurance charge, and credibility of the CEO.

However, Tusa views the key aspect as more clarity on de-leveraging around where the "value" of the assets is going, and then the "ongoing lack of visibility on the simple math that shows a negative run rate" on enterprise free cash flow fully diluted for portfolio moves. Even assuming a recovery in Power, "one has to make highly optimistic assumptions to get back to a run rate that supports anything near $10" per share, Tusa writes. In vowing to "stick to the numbers," Tusa says his read through from GE's Q4 results reaffirms his "well below-consensus model."

Overall, "there was a lack of tangible details on key items," Tusa contends. He keeps a Neutral rating on General Electric with a $6 price target.