Boeing Co (NYSE:BA) has been one of the hottest stocks in the market recently. It’s up 15% over the past 5 days, 24% over the past month and almost 60% year-to-date.

The most recent leg higher in the stock started with blowout second-quarter earnings numbers last Wednesday. The big story in that report? Cash flow.

Cash flows have always been the storyline at Boeing. The company produces giant amounts of cash, spends some of it on capital expenditures and returns the rest of it to shareholders via buybacks and dividends. This cash flow dynamic has made BA stock a safe place for investors to hang out. Big yields and buybacks can help offset operational weakness.

This year, cash flows are up across the board. Boeing generated operating cash flow of $5 billion in the second of 2017, versus just $3.2 billion in the same quarter last year. This robust cash flow growth is expected to continue not only this year, but every year into 2020.

Robust cash flow growth translates into investors bidding up the stock. BA stock now sits at all-time highs.

But is this a rally investors should chase?

Not really. Here’s why.

Growth Catalysts Are Already Priced Into Boeing

Undoubtedly, Boeing finds itself as the beneficiary of multiple secular growth tailwinds.

In the commercial airline market, increased airline traffic and profitability is having a positive effect on BA results. Passenger traffic continues to outpace GDP, and that is largely a result of today’s experience-driven economy. The more younger consumers value experiences, the more they will travel. This is a secular tailwind that should remain in place into the foreseeable future.

Moreover, increased airline profitability is driving greater stability and reducing how cyclical the industry is. Consequently, Boeing is upping production to match this more stable demand flow. This is also a multiquarter tailwind that will prop up operating results and drive greater profitability.

On the defense side, Boeing is winning because of President Donald Trump and North Korea. Trump wants to up the fiscal 2018 defense budget. If successful, that would be a huge tailwind for Boeing’s defense business. Meanwhile, North Korea continues to get more aggressive with its ballistic missile tests. Kim Jong Un recently said that the entire United States was in range of North Korea’s ICBM. That creates a tailwind for missile defense spending.

And it’s already happening. During the quarter, Boeing won a $1 billion award from the U.S. Missile Defense Agency.

But all of these catalysts are priced into BA stock. Management’s new guide calls for core earnings per share of $9.80 this year. That is up 35% year-over-year. Next year, core EPS is projected to be up another 8%. Overall, over the next five years, analysts see earnings growth hovering around 18% per year.

But at $245, BA stock is trading at 25 times this year’s projected core EPS of $9.80. A 25-times multiple for 18% growth implies that BA stock is fully valued at these levels.

Bottom Line on BA Stock

The valuation is rich now. Per YCharts, the stock’s 30x trailing price-to-earnings multiple is a five-year high. The 14x trailing price-to-operating cash flow multiple is 52-week high. The 17x trailing price-to-free cash flow multiple is also a 52-week high.

The last time the free cash flow yield was this low (~6%) was in mid-2015. BA stock proceeded to simply move sideways from that point to the back half of 2016. It wasn’t until the free cash flow yield crept back up to 9.5% by the back-half of 2016 that BA stock proceeded to take off.

In other words, BA stock feels fully valued here. The free cash flow yield has depressed to levels that imply limited upside over the next several months.

As of this writing, Luke Lango did not hold a position in any of the aforementioned securities.