The latest 13F season is commencing, when many money managers issue required reports on their holdings. It can be worthwhile to pay attention, as you might get an investment idea or two by seeing what some major investors have been buying and selling.

For example, consider GAMCO Investors (GBL 4.25%), the diversified asset-manager and financial-services company headed by well-known value investor Mario Gabelli. According to its recently released 13F statement, the company upped its positions in Boyd Gaming Corporation (BYD 2.18%), Hartford Financial Services Group (HIG -0.72%), and Hewlett-Packard Company (HPQ 0.36%).

Boyd Gaming is a domestic casino operator, owning the Borgata property in Atlantic City, along with operations in Las Vegas and elsewhere. Bears worry about its debt load, which has been rising in recent years. Bulls like that the company is involved in online gambling, with revenue there growing 15% in January. It has more than 40% of the online gambling market in New Jersey and is rolling out gambling apps for smartphones and mobile devices. Analysts at FBR Capital Markets recently upgraded the stock, citing effective cost-cutting and expected improvement in Las Vegas. Boyd Gaming announces its latest quarterly results in early March and ahead of that it recently lowered its projections. (This, oddly, sent its shares up -- presumably because investors had expected even lower numbers.)

Hartford Financial Services Group has been shifting its focus from annuities, retirement planning, and life insurance toward property and casualty insurance. It's also working to reduce its significant debt. Following a strong third quarter, the company's fourth quarter featured core earnings up 78% thanks in part to price hikes. The company's outlook for 7% growth in 2014 sent shares down, though, as investors were hoping for more (though they possibly overreacted). Hartford Financial's dividend was hiked by 50% last year and recently yielded 1.7%.

Hewlett-Packard yields 1.9% and has a forward P/E ratio near eight, making it look quite attractive. It requires a lot more digging and thought, though, as some think the company may be dying, pointing to "several years of declining revenues and earnings due to internal strife, missteps, and a stubborn adherence to a dying PC industry." The stock has surged more than 80% over the past year, but that's partly due to cost-cutting that included a lot of layoffs. Hewlett-Packard seems to be exiting the mobile arena, selling its mobile patents to Qualcomm. This is seen by some as a welcome sign of increased focus on higher-margin opportunities instead of hardware. Still, the company faces many challenges, such as a weak PC market.