From the outset, let me say that there are a number of factors that could affect the analysis below. Nevertheless, sticking close to the facts, it seems to me that Romney either lied about the value of Staples in his divorce case testimony, displayed terrible judgement as an investor or both.der knowledge.
Staples went public in late 1989/early 1990 at $20/share. The stock ranged from about $27-30/share during June 1991 when Romney testified that it was overvalued. It stayed in that range (accounting for a stock split) until the third week in September 1991 and then went up for some years to come.
From this, I conclude that
1. Romney lied and committed perjury. (Note that the market, which according to Romney is the true arbiter of value, obviously disagreed.);
2. Displayed horrible judgement regarding his investment in Staples given that the stock continued to increase in value way beyond when he sold to Goldman Sachs; or
3. Both.