MW April 15 is tax deadline day - but here's why it's also important for the stock market.

By Barbara Kollmeyer

Less money flowing through the market isn't a problem unless the Iran war takes a turn for the worse, say strategists

April 15 is also significant to the stock market.

Happy tax day (or not) to those who observe.

April 15 also happens to be an important calendar event for the stock market, say researchers at institutional brokerage firm Strategas Securities who warn a vital "liquidity boom" that has been supporting markets during the Iran conflict is about to slow.

This comes just as they see investors growing increasingly optimistic about a deal to end the Middle East unrest.

A team led by Daniel Clifton, head of policy research at Strategas, noted that financial markets have been getting a timely, helping hand from around $700 billion in stimulus that's been working its way through the system this year.

Strategas

That stimulus includes tax refunds, 100% expensing of business investment, mortgage-backed securities purchases and financial deregulation, they noted. But tax refunds are now shifting to tax payments.

Clifton and his team noted that taxpayers who are set to get a refund often file early, which leads to the Treasury making tax refund payments for February and March and drawing down its Treasury General Account. Those who need to make tax payments tend to file around the April 15 deadline.

"We estimate that non-withheld tax payments will drain more than $500 billion (gross) from the banking system in the next three weeks," they said. "The Fed has been expanding its balance sheet since December to build bank reserves in the system to absorb this temporary loss of reserves."

The New York Fed said Monday that it will slow the central bank's balance sheet expansion from a net $40 billion per month to $25 billion in Treasury bill purchases. The plan to slow that after tax payments finish wasn't a big surprise, and the final purchase number was a bit better than markets expected. But it still marks a "step down in terms of liquidity," the analysts noted.

"This is all manageable should policymakers directionally move to an Iran deal, but a re-escalation with less liquidity will be tougher to chew on for investors if no deal is reached," they said.

Strategas said in recent chats with investors, most have mentioned how the S&P 500 SPX is now trading above where it stood before the Iran war. Investors appeared "emboldened" by those headlines, but the researchers are wary about market direction in light of a disruption to that big liquidity cushion.

For investors banking on an Iran deal to keep the market party going, Clifton and his team urge them to keep four questions in mind:

-- Will the U.S. blockade of the Strait of Hormuz be effective

-- Will the Houthis close off another key oil chokepoint, the Bab al-Mandeb Strait?

-- Will China challenge the blockade?

-- Will a second meeting between Iran and the U.S. happen soon?

The markets

U.S. stock futures (ES00) (YM00) (NQ00) are pointing to a slightly weaker open, while oil prices (CL.1) (BRN00) are rising.

   Key asset performance                                                Last       5d      1m      YTD     1y 
   S&P 500                                                              6967.38    5.30%   3.74%   1.78%   29.11% 
   Nasdaq Composite                                                     23,639.08  7.36%   5.16%   1.71%   40.52% 
   10-year Treasury                                                     4.266      -3.50   0.10    9.40    -1.60 
   Gold                                                                 4821.2     1.61%   -0.05%  11.29%  43.59% 
   Oil                                                                  92.55      -4.09%  -6.55%  61.21%  49.42% 
   Data: MarketWatch. Treasury yields change expressed in basis points 

The buzz

The U.S. blockade in the Strait of Hormuz has stopped eight oil tankers. President Donald Trump told the New York Post that talks aimed at ending the war in Iran could restart this week.

Bank of America (BAC) and Morgan Stanley $(MS)$ will release first-quarter earnings.

Snap (SNAP) said it would cut 16% of its global workforce.

ASML $(ASML)$ lifted its 2026 sales forecast, thanks to strong demand for chips from the AI sector.

Import prices for March are due at 8:30 a.m., along with the Empire State manufacturing index for April. The NAHB/Wells Fargo Housing Market Index is due at 10 a.m., followed by the Fed Beige Book of economic activity at 2 p.m.

Fed Gov. Michael Barr will give a speech at 8:30 a.m. and Fed Vice Chair for Supervision Michelle Bowman will speak at 1:45 p.m.

Best of the web

How elderly Americans amassed disproportionate wealth and power.

Jeanine Pirro's prosecutors make surprise visit to Fed headquarters.

Missing nuclear official becomes 10th tied to U.S. secrets.

The chart

The Citigroup chart shows how growth and price momentum stocks have been driving the recent rally for the S&P 500 SPX, as Iran war news has turned more hopeful and first-quarter earnings kick off. The combination of long growth and long momentum has jumped 26% since the market low on March 30, noted the Citi equity trading team led by Stuart Kaiser. He said they still like those stocks, but with the S&P 500 nearing 7,000 and the Cboe Volatility Index, or VIX VIX, down to 18.4, their preference is for call options - the right to buy an asset at a future date at a fixed price - on the Nasdaq-100 tracking Invesco QQQ Trust Series I QQQ QQQ.

Top tickers

These were the top-searched tickers on MarketWatch as of 6 a.m.:

   Ticker  Security name 
   NVDA    Nvidia 
   TSLA    Tesla 
   AMD     Advanced Micro Devices 
   GME     GameStop 
   PLTR    Palantir 
   TSM     Taiwan Semiconductor Manufacturing 
   MU      Micron 
   MSFT    Microsoft 
   ORCL    Oracle 
   AAPL    Apple 

Random reads

Ready for takeoff - Air New Zealand's economy sleep pods.

Actor Timothée Chalamet is suddenly ballet and opera's BFF.

"Syd for short." Guess who's back with a new American Eagle campaign?

BEYOND THE NEWS

MarketWatch Picks: 13 states where home prices are falling - and what home buyers should know now

-Barbara Kollmeyer

This content was created by MarketWatch, which is operated by Dow Jones & Co. MarketWatch is published independently from Dow Jones Newswires and The Wall Street Journal.

(END) Dow Jones Newswires

April 15, 2026 06:58 ET (10:58 GMT)

Copyright (c) 2026 Dow Jones & Company, Inc.